Implantable restriction system with load monitor

ABSTRACT

An apparatus for regulating the functioning of a patient&#39;s organ or duct includes an elongated member having a first end and a second end. A fastener is disposed on the first end of the elongated member. The fastener is configured to engage the second end of the elongated member so that the elongated member forms a loop around the organ or duct. A tension element is disposed for movement within the elongated member. A drive element is associated with and engages the tension element for causing the tension element to control the tension applied by the elongated member against a patient&#39;s body organ or duct. A load monitor ensures that excessive pressure is not applied to a patient&#39;s body organ or duct.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to laparoscopic implanted restriction systemdesigned to be implanted in the body of a patient around a biologicalorgan having a pouch or duct to regulate functioning of the organ orduct. More specifically, the present invention is directed to animplantable telemetrically powered and controlled ring suitable for useas a gastric band to treat obesity or as an artificial sphincter.

2. Description of the Related Art

Obesity refers to a body weight that exceeds the body's skeletal andphysical standards. One well recognized parameter used to measureobesity is Body Mass Index (BMI), because it takes into account patientheight and not just weight. BMI is calculated by dividing weight byheight squared and is expressed in kg/m2.

Obesity is well recognized as a serious health problem, and isassociated with numerous health complications, ranging from non-fatalconditions to life-threatening chronic diseases. Surgical interventiongenerally is the treatment of choice for patients afflicted with morbidobesity. Such intervention not only mitigates the myriad of healthproblems arising from being overweight, but may also reduce the risk ofearly death of the patient. Left untreated, morbid obesity may reduce apatient's life expectancy by ten to fifteen years.

Morbidly obese patients as a group are poorly adapted to attainsustainable long-term weight loss using non-surgical approaches, such asstrict diets combined with exercise and behavioral modification, eventhough such methods are acknowledged to be the safest. For this reason,there is a continuing need for direct intervention to provide effective,long-term treatments for morbid obesity. Three main surgical proceduresare currently in use: Roux-en-Y Gastric Bypass (“RYGB”), Vertical BandedGastroplasty (“VBG”) and Adjustable Gastric Banding (“AGB”).

In RYGB a small stomach pouch is created and a Y-shaped section of thesmall intestine is attached to the pouch so that food bypasses the lowerstomach, the duodenum and the first portion of the jejunum. The RYGBprocedure is both restrictive, in that the small pouch limits foodintake and malabsorptive, in that the bypass reduces the amount ofcalories and nutrients the body absorbs.

VBG employs a non-adjustable synthetic band and staples to create asmall stomach pouch. AGB employs a constricting synthetic ring defininga gastric band that is placed around the upper end of the stomach tocreate an artificial stoma within the stomach. The band is filled withsaline solution and is connected to a small reservoir/access-portlocated under the skin of the abdomen. The AGB band may be inflated,thereby reducing the size of the stoma, or deflated, thus enlarging thestoma, by puncturing the access-port with a needle and adding orremoving saline solution. Both VBG and AGB are purely restrictiveprocedures, and have no malabsorptive effect.

It is sometimes necessary to re-operate, either to relieve the patientor to adjust or change the previously implanted band. In such cases, thepreviously implanted band must be cut and either removed or replaced.These operations are difficult to carry out, difficult for the patientto tolerate and costly.

Several attempts to overcome the drawbacks associated with hydraulicallyactuated gastric bands, are found in the prior art. For example U.S.Pat. No. 6,547,801 to Dargent et al. describes a surgically implantedgastroplasty system having a flexible tactile element that engages amotor-driven notched pulling member. The motor is powered and controlledby an inductive circuit, so that the diameter of the ring may only bechanged by operation of an external remote control.

All of the foregoing surgical techniques involve major surgery and maygive rise to severe complications. Recent developments have focused onthe use of laparoscopic implantation of the gastric ring to minimizepatient discomfort and recuperation time.

In view of the foregoing, it would be desirable to provide apparatusesand methods for regulating functioning of a body organ or duct thatprovides high precision in controlling the degree of constrictionimposed upon the organ or duct, without the drawbacks associated withprior control mechanisms.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide anapparatus for regulating the functioning of a patient's organ or ductincluding an elongated member having a first end and a second end. Afastener is disposed on the first end of the elongated member. Thefastener is configured to engage the second end of the elongated memberso that the elongated member forms a loop around the organ or duct. Atension element is disposed for movement within the elongated member. Adrive element is associated with and engages the tension element forcausing the tension element to control the tension applied by theelongated member against a patient's body organ or duct. A load monitorensures that excessive pressure is not applied to a patient's body organor duct.

It is also an object of the present invention to provide an apparatuswherein the load monitor includes a monitoring circuit monitoringcurrent drawn by the drive element.

It is a further object of the present invention to provide an apparatuswherein drive element is motor.

It is another object of the present invention to provide and apparatuswherein the monitoring circuit is a closed loop feedback circuit.

It is also an object of the present invention to provide an apparatuswherein the monitoring circuit includes leads accessing current flowingfrom a power source to a motor of the drive element.

It is a further object of the present invention to provide an apparatuswherein the current is measured using a current sensing circuit andoutput current measurement is forward to a microcontroller for controlof the drive element.

It is another object of the present invention to provide and apparatuswherein the monitoring circuit includes a Hall sensor positioned about awire supplying a motor of the drive element with electrical power.

It is also an object of the present invention to provide an apparatuswherein load monitor is a strain gage.

It is a further object of the present invention to provide an apparatuswherein the drive element includes a motor acting upon threading of thetension element and the strain gage measures tension applied to thethreading of the tension element.

It is another object of the present invention to provide and apparatuswherein the load monitor includes a pressure monitor associated with afluid filled bladder forming part of the elongated member.

It is also an object of the present invention to provide an apparatuswherein the fluid filled bladder is formed along the interior surface ofthe elongated member.

It is a further object of the present invention to provide an apparatuswherein the fluid bladder is a separate component and may be added orfixedly attached to the elongated member prior to or duringinstallation.

It is another object of the present invention to provide and apparatuswherein the fluid filled bladder is pre-filled with fluid and calibratedprior to implantation.

It is also an object of the present invention to provide an apparatuswherein the fluid filled bladder may be fluid calibrated postimplantation.

It is a further object of the present invention to provide an apparatuswherein the fluid filled bladder is adjustable.

It is another object of the present invention to provide and apparatuswherein the fluid filled bladder is provided with a port in fluidcommunication with a filling tube that extends from the fluid bladder.

It is also an object of the present invention to provide an apparatuswherein fluid within the fluid bladder is a non-aqueous fluid or gel.

It is a further object of the present invention to provide an apparatuswherein load monitor includes a torque sensor measuring the motortorque.

Other objects and advantages of the present invention will becomeapparent from the following detailed description when viewed inconjunction with the accompanying drawings, which set forth certainembodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a banding system in accordance with thepresent invention.

FIGS. 2A and 2B are, respectively, a schematic diagram, partly incross-section, of the gastric band of FIG. 1 and a sectional view takenalong line 2B-2B of FIG. 2A.

FIGS. 3 to 14 show various embodiments enhancing the interior surface ofthe ring for contact with tissue.

FIGS. 15A and 15B are perspective views illustrating the degree ofconstriction attainable by the ring of the present invention between thefully open and fully closed positions.

FIGS. 16A and 16B are cross-sectional views of the ring of the presentinvention along the lines 16A-16A and 16B-16B of FIGS. 15A and 15B,respectively.

FIG. 17 is a partial perspective view of a screw thread portion of thetension element of the present invention.

FIG. 18 is a perspective view of an entire tension element suitable foruse in the ring of the present invention.

FIG. 19 is a perspective view of the tension element of FIG. 6 coupledto the rigid dorsal peripheral portion and motor housing of the ring.

FIG. 20 is a perspective view of the ring of FIG. 1 straightened andinserted within a standard 18 mm trocar.

FIG. 21 is a cross-sectional view of an elastomeric housing of thegastric band depicting the path of the antenna wire and cavity thataccepts the tension element.

FIG. 22 is a perspective view of the drive element housing, tensionelement and drive element of the present invention.

FIG. 23 is a perspective view of the tension element engaged with thedrive element.

FIG. 24 is a cross-sectional view of a tension element in accordancewith an alternate embodiment.

FIG. 25 is a cross-sectional view depicting the construction of thedrive element of FIG. 23.

FIG. 26 is a cross-sectional view depicting the construction of thereference position switch.

FIGS. 27 to 38 show various embodiments of drive assemblies, which maybe used in accordance with the present invention.

FIGS. 39 to 55 show various embodiments for releasing the fixed end ofthe tension element from its position at the second end of the ring.

FIGS. 56A-C show another embodiment of implementing a balloon basedback-up system in conjunction with the mechanical tension element.

FIGS. 57A, 57B and 58A, 58B show a couple embodiments of releasing fluidfrom the secondary cavity of the ring.

FIGS. 59 to 71 show various embodiments for releasing the tensionelement.

FIG. 72 is a schematic showing an alternate embodiment with a titaniumcase encasing electronic components of the invention.

FIGS. 73 to 76 show additional embodiments for releasing the tensionelement.

FIGS. 77 to 94 show various embodiments for releasing the free end ofthe tension element from engagement with the drive element in accordancewith the present invention.

FIGS. 95 and 96 show embodiments for accessing the electronic controlsof the antenna/controller pod for controlling operation of the ring inaccordance with the present invention.

FIGS. 97A and 97B are perspective views illustrating the clip used toclose the ring into a loop.

FIGS. 98 and 99 show a release mechanism for a clip of the ring inaccordance with an alternate embodiment of the present invention.

FIG. 100 is a perspective view of the antenna/controller pod of thepresent invention.

FIG. 101 is a cut-away view of the interior of the implantableantenna/controller pod of FIG. 100.

FIG. 102 is a cross-sectional view of the antenna cable of FIG. 100.

FIG. 103 is a detailed view of the signal strength indicator portion ofthe remote control of FIG. 1.

FIG. 104 is a schematic diagram illustrating placement of theimplantable portion of the present invention within a patient.

FIG. 105 is a schematic view of the telemetric power and controlcircuitry of the present invention.

FIGS. 106 to 112 show various embodiments for monitoring the tensionapplied by the ring.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The detailed embodiments of the present invention are disclosed herein.It should be understood, however, that the disclosed embodiments aremerely exemplary of the invention, which may be embodied in variousforms. Therefore, the details disclosed herein are not to be interpretedas limiting, but merely as a basis for teaching one skilled in the arthow to make and/or use the invention.

Referring now to FIG. 1, the banding or implantable restriction system 1of the present invention is described. The banding system 1 includes anexternal control 10 and implantable gastric band 21. In the followingdescription reference will be made, by way of illustration, to a gastricband 21 in the form of a ring 22 designed to be implanted around thestomach to selectively adjust the diameter of the opening of the stoma,and thereby control food intake. Such regulation has the effect ofcreating a feeling of satiety in the patient after relatively littlefood is consumed, and provides an effective treatment for morbidobesity.

It is to be understood, however, that the present invention is in no waylimited to gastroplasty, but on the contrary, advantageously may beapplied to regulate the functioning of other body organs or ducts, suchas in the treatment of gastro-esophageal reflux disease, urinary orfecal incontinence, colostomy, ileostomy or to regulate blood flow inconnection with isolated organ perfusion for treatment of cancer. Whenapplied in the treatment of urinary continence, the implantable portionof the present banding system 1, in particular, the elongated member inthe form of a ring 22 will be implanted around the bladder or urinarytract, while in the case of fecal incontinence, the ring 22 may beimplanted around a portion of the gastro-intestinal tracts, such as analstructures of the intestine. With this in mind, the present bandingsystem 1 is MRI compatible and all elements thereof arenon-ferro-magnetic.

As discussed above, the present invention relates to an implantablerestriction system. A preferred embodiment of the implantablerestriction system is disclosed herein with reference to a gastric bandused in restricting the effective size of the stomach for application inbariatric procedures. As such, the implantable restriction system of thepresent invention is referred to as including a gastric band or ringthroughout the present disclosure, although those skilled in the artwill appreciate the concepts underlying the present invention may beapplied in a variety of implantable restriction devices as brieflydiscussed above.

System Overview

With respect to FIG. 1, the self-contained external control 10 comprisesa housing 11 having a control panel 12 and a display screen 13. Theexternal control 10 includes a digital signal processor and may bebattery-powered or powered using an external power supply, e.g.,connected to an electric wall outlet. An external antenna 14 is coupledto the external control 10 via a cable 15. As described more fully withrespect to FIG. 105, the external control 10 includes a controller (suchas a microprocessor) that controls the emission of radiofrequencysignals to the gastric band 21 to both control and power operation ofthe gastric band 21.

The external control 10 accepts a patient microchip card 16, whichcorresponds to the specific gastric band 21 implanted in the patient,and stores data, such as the implant identification number, adjustmentparameters (e.g., upper and lower limits of an adjustment range, etc.)and information regarding the last adjustment position of the ring 22.The external control 10 as shown in FIG. 1 includes a signal strengthindicator 17, as described in more detail below with respect to FIG.103, an ON/OFF button 18, an OPEN button 19 a, a CLOSE button 19 b, aCOUPLING button 19 c and a menu options panel 20.

During use of the present banding system 1, the physician need only turnon external control 10 using the ON/OFF button 18, position the externalantenna 14 over the patient's chest above antenna/controller pod 23,check the coupling by depressing the COUPLING button 19 c, and when thecoupling is sufficient, adjust the degree of constriction using the OPENbutton 19 a or the CLOSE button 19 b to control the effectivecircumference of the ring 22 in a manner discussed below in greaterdetail. The diameter of the gastric band 21 is continually displayed onthe display screen 13 with a precision of about 0.1 mm for the entirerange of diameters of the ring 22, e.g., from 19 mm fully closed to 29mm fully opened.

Still referring to FIG. 1 and as briefly mentioned above, the gastricband 21 of the present invention includes a ring 22 coupled to animplantable antenna/controller pod 23 via an antenna cable 24. Theantenna/controller pod 23 includes a removable tag 25 that may be usedto laparoscopically position the ring 22. The ring 22 includes a firstend 26 having a clip 27 that slides over and positively engages a secondend 28 of the ring 22.

As described in detail below, the ring 22 is configured to bestraightened to pass through the lumen of a commercially available 18 mmtrocar for delivery to a patient's abdomen (see FIG. 20). The tag 25,antenna/controller pod 23 and antenna cable 24 are passed through a clip27 to form the gastric band 21 into a substantially circular ring 22around an upper portion of the patient's stomach, thereby reducing thediameter of the opening of the stomach. In its undeformed shape, thering 22 assumes a circular arc configuration that facilitatespositioning of the ring 22 around the stomach and also in self-guidingthe clipping procedure.

The ring 22 of the present invention comprises a flexible tubular memberhaving a smooth, flexible and elastic membrane, thus ensuring atraumaticcontact with the patient's stomach tissue that is easily tolerated. Whenengaged with a dorsal element 38, the membrane 39 is stretched by anappropriate factor (i.e., 20%-40%), so that when the ring 22 is in it'sfully closed position, little or no wrinkling appears on the membranesurface. The ring 22 has approximately the shape of a torus ofrevolution of substantially cylindrical cross-section. Alternatively,the ring 22 may have other suitable cross-sections, includingrectangular. The housing 29 on the second end 28 of the ring 22, theclip 27 on the first end 26 of the ring 22 and the dorsal peripheralportion 30 of the ring 22, preferably are made of a biocompatiblematerial such as silicone. An interior portion 31 of the ring 22 may beconstructed in a variety of manners as discussed below in greater detailto permit engagement with the tissue without bunching or rippling, and,as discussed below in greater detail, may be covered in various mannersto enhance the ring/tissue interface and protect the ring 22.

Implantable Ring

Referring now to FIGS. 2A and 2B, the internal structure of the ring 22is described. In particular, and as depicted in FIG. 2A, the ring 22includes a flexible tension element 32 having a fixed end 33 staticallymounted to the first end 26 of the ring 22 and a free end 34 that isengaged with a motor-driven drive element 35 and extends into a cavityin the housing 29. The tension element 32 is slidingly disposed within asubstantially cylindrical tube of a compressible material 36, e.g.,ePTFE, as illustrated in FIG. 2B, so that when the tension element 32 ispulled through the drive element 35, the compressible material 36 iscompressed and the diameter of opening 37 is reduced. The compressiblematerial 36 is preferably surrounded on its dorsal face by a dorsalelement 38. The dorsal element 38 is flexible, but sturdier than theelastomeric material of the compressible material. The dorsal element ispreferably composed of silicone. Both the compressible material 36 andthe silicone dorsal element 38 preferably are enclosed within a membrane39 of elastomeric biocompatible material, as shown in FIG. 2B, toprevent tissue in-growth between the ePTFE compressible material 36 andthe silicone dorsal element 38. The membrane 39 may be affixed to thedorsal element 38 using a biocompatible glue to prevent leakage in caseof accidental puncture on the dorsal surface.

With reference to FIGS. 3 to 14, various embodiments have been developedfor improving the interaction between the inner surface 112 of the ring22 and the tissue it engages as the band 21 is constricted about thestomach of a patient. In accordance with a first embodiment as shownwith reference to FIG. 3, a fluid bladder 114 is added to the innersurface 112 along the internal circumference of the ring 22 such thatthe fluid bladder 114 interfaces with the tissue. In addition, toimproving the tissue band interface, the addition of a fluid bladder 114along the inner surface 112 of the ring 22 allows for ready adjustmentsto the restrictive level of the ring 22.

In accordance with such an embodiment, and as briefly discussed above,the fluid bladder 114 is formed along the inner surface 112 of the ring22 for direct engagement with the tissue when the ring 22 is applied tothe stomach and constricted thereabout. The fluid bladder 114 ispreferably made of silicone (or other biocompatible material) and isconstructed as an elongated cylindrical member 116 with a high degree offlexibility allowing it to conform to the surface of the tissue to whichit is applied without adversely affecting the tissue when appliedthereto for long periods of time. The cylindrical member 116 extendsabout substantially the entire length of the inner circumference of thering 22. As such, the fluid bladder 114 includes a first end 118adjacent the first end 26 of the ring 22 and a second end 120 adjacentthe second end 28 of the ring 22.

The cylindrical member 116 includes a central lumen 121 shaped anddimensioned to receive a filling fluid as discussed below. Thecylindrical member 116, and ultimately the central lumen 121, includesthe closed first end 118 and the open second end 120. The second end 120is provided with a port 122 in fluid communication with a filling tube124 that extends from the fluid bladder 114 to a remote fluid source 126allowing for the controlled application of the fluid to the fluidbladder 114 for filling thereof as desired by the medical practitionerdeploying and installing the present ring 22. In accordance with such anembodiment, it is contemplated the remote source of fluid 126 could beintegrated with the antenna/controller pod 23 as discussed below ingreater detail.

The filling tube 124 is provided with a first end 128 which is securedto the port 122 of the fluid bladder 114 and a second end 130 positionedremote from the first end 128. The second end 130 is fixedly orselectively secured to a source of fluid 126 for filling the fluidbladder 114 as one may desire in accordance with the principles of thepresent invention. In accordance with a preferred embodiment, the fluidsource 126 is a miniature fill port which is subcutaneously implanted(for example, in conjunction with the antenna/controller pod 23) foraccess and addition of fluid as required by the needs of the patientbeing treated. The fill port 126 includes a flexible access septum 129through which the medical practitioner may access the internal cavity131 of the fill port 126 for increasing or decreasing the volume offluid applied to the fluid bladder 114 positioned along the innersurface 112 of the ring 22 and in direct contact with the tissue of thestomach.

It is further contemplated that to achieve a softer tissue interfacewithout secondary adjustability, the fluid bladder may be prefilledprior to implantation. Where such an implementation is employed, a fluidport would not be required. The fluid could be added directly through acatheter attached to the fluid bladder. Once added, the fluid would betrapped by plugging the catheter (for example, tying in a knot, adding afluid plug, lues activated valve, etc.).

In the event of a mechanical or electrical adjustment feature failurethe fluid bladder would allow at least minor adjustments to the band.The fluid bladder can be used as a safety feature in case the mechanicaladjustment is not functioning properly, since fluid could easily beremoved from the bladder un-tightening the gastric band and relievingthe pressure applied to the stomach.

It is contemplated the fluid bladder could be prefilled with a substanceor solution prior to installation. Where the fluid bladder is prefilled,the fluid within the fluid bladder is hyper-osmolar relative to theimplanted physiological environment. For example, the filling fluid maybe a salt solution or ionic polymer solution, sodium alginate, sodiumhyaluronate, etc. The fluid may also be hypo-osmolar relative to theimplanted physiological environment, such as, a non-ionic polymersolution poly(ethylene glycol). The fluid may also be a non-Newtonianfluid, such as, a polymer solution selected from the group consisting ofa poly(vinylpyrrolidone), carboxymethylcellulose, poly(ethylene glycol),poly(acrylamid), sodium hyaluronate, hyaluronic acid, and alginates. Thefluid may further be a non-aqueous fluid or gel, such as, a silicone oilor fluorosilicone oil.

In accordance with an alternate embodiment, the ring 22 is shaped anddimensioned to provide for more compliant material and/or constructionby altering the cross sectional geometry of the ring 22 to reduce thespring constant of the compressible material 36 between the tensionelement 32 and the tissue. In addition, improved compliance andconstruction are achieved by altering the construction of the gastricband 21 such that a secondary, softer material is introduced into thespace between the tension element 32 and the tissue, giving the gastricband 21 a reduced spring constant. Improved compliance and constructionis further achieved by combining a reduced spring constant with aviscoelastic filler material to give viscoelastic (or rate dependent)deformation characteristics.

In accordance with this embodiment, and as show with reference toembodiments shown in FIGS. 4 to 8,variations in the spring constant ofthe gastric band 21 between the tension element 32 and the tissue isachieved through the formation of longitudinally extending space(s) 132within the compressible material 36. In accordance with a preferredembodiment, the space(s) 132 maintains a constant shape along the lengthof the compressible material 36, although it is contemplated the shapesof the space(s) 132 may be varied along the length of the compressiblematerial 36 and the ring 22. In practice of the present embodiment, thespring constants may be derived or inferred from tissue interfacepressures in the range of −100 mmHg to 300 mmHg gauge pressure whereinthe basic relationship is determined by the formula p=F/A. However, itis also contemplated pressures outside this range may also be used.

The space(s) 132 may be filled with another material such as siliconerubber, a lower durometer polymer or closed-cell foam to give a reducedspring constant. The space(s) 132 within the cross section may alsoinclude viscous or viscoelastic filler materials. That is, theydemonstrate rate dependent response to dynamic force conditions such asthe passage of food through the esophagus. Potentialviscous/viscoelastic filler materials include, but are not limited to,saline liquid or gel silicone, biogels, close cell foams, or packgranules or spears of one or more materials.

In addition to improving the spring constant, the incorporation of openspace(s) 132 in the compressible material 36 as disclosed hereinmaximizes the interface between the ring 22 and the tissue therebyspreading the forces or interface pressures applied to the tissue inaccordance with the present invention.

As discussed above, the space(s) 132 may take a variety of forms. Forexample, and with reference to FIG. 4, the space 132 takes the form of asubstantially C-shaped lumen. In accordance with an alternate embodimentas shown with reference to FIG. 5, the space 132 takes the form oftruncated triangle wherein the top section (that is, the narrow portionadjacent the tension element 32) of the triangle is curved and thebottom section (that is, the wide portion removed from the tensionelement 32) of the triangle includes a slightly concave base. Inaccordance with yet a further embodiment, and with reference to FIG. 6,first and second arcuate spaces 132 are provided on opposite sides ofthe ring 22. Once again, and with reference to FIG. 7, four elongatedspaces 132 are provided. The elongated spaces 132 are oriented such thatwhen viewed across the cross section of the ring 22, the longitudinalaxis thereof extends transversely against the longitudinal axis passingthrough the center of the ring 22. In accordance with yet a furtherembodiment, and with reference to FIG. 8, the spaces 132 are formed soas to extend circumferentially about the compressible material 36 of thering 22 and take the form of arcuate members whose concave surfaces 134faces away from the center of the ring 22 and whose convex surfaces 136face away from the center of the ring 22.

In accordance with yet another embodiment of the present invention, andwith reference to FIG. 9, the ring 22, and in particular, thecompressible material 36, may be provided with a fluid chamber 138extending along the inner circumferential portion of the compressiblematerial 36. In contrast to the embodiment disclosed above withreference to FIG. 3, the fluid lumen or chamber 138 forms part of thecompressible material and is preferably integrally formed with thecompressible material 36. As such, the compressible material 36 may bethought of as including a fluid lumen 138 along its inner surface, thefluid lumen 138 being shaped and dimensioned for maintaining a desiredfluid therein so as to improve the stress profile being applied to thetissue.

In accordance with a preferred embodiment of the present invention, thefluid chamber 138 includes a cross-sectional profile, when viewed alonga plane transverse to the circumferential axis running along the centerof the ring 22, that remains constant along the length of the ring 22.The profile is elliptical defining an arcuate inner wall 140 and anarcuate outer wall 142 with the concave surfaces thereof facing eachother.

In addition to improving the tissue to ring interface by providinggreater compliance along this area, the fluid chamber 138 may also allowfor expansion of the gastric band 21 in the event the mechanicaladjustment system fails. In particular, the fluid lumen 138 ismaintained in fluid communication with a remote fluid pressure source asdiscussed above with reference to FIG. 3. As such, and if the mechanicalor electrical adjustment feature fails, fluid may be pumped into thefluid lumen 138 creating additional pressure that is transferred to thestomach about which the ring 22 is positioned. Alternatively, fluid maybe removed from the fluid lumen 138 thereby relieving pressure appliedto the stomach about which the ring 22 is positioned. In accordance witha preferred embodiment, it is contemplated the fluid source may behoused in and controlled by the antenna/controller pod 23 of the ring22. It is further contemplated, the fluid source may also be manuallyadjusted by a separate connection to a fluid port.

In accordance with still a further embodiment, the cross-sectionalgeometry of the gastric band 21 may be varied to cover otheralternatives. As shown with reference to FIG. 10, the geometry isaltered such that the tension element 32 is positioned off center of thecompressible material 36, that is, the cross sectional area of the ring22 itself. By doing this, the tension element 32 takes advantage ofrotational torque resulting from the off center positioning and producesmechanical advantages during the constriction of the ring 22.

With reference to the embodiments shown with reference to FIGS. 12 and13, a softer tissue ring interface is achieved by positioning a flexiblestrip 146 along the inner surface 112 of the ring 22, and between thecompressible material 36 and the membrane 39. This strip 146 is designedto spread the forces of the tension element 32 along the entirecircumference of the ring 22 and is preferably made from a polymer. Withreference to FIG. 11, the strip 146 is placed along the inner surface112 of the ring 22, and not between the compressible material 36 and themembrane 39. In accordance with a preferred embodiment, the strip 146includes an inner surface 148 and an outer surface 150. The innersurface 148 is substantially smooth and flat and is adapted to directlyface the tissue upon constriction of the ring 22, with the strip 146positioned between the compressible material 36 and the membrane 39. Theouter surface 150 includes substantially flat portions 152 and a centralprotrusion 154 which is shaped and dimensioned to directly engage thetension element 32 upon constriction thereof. As such, and when thetension element 32 is tightened, the tension element 32 applies pressuredirectly to the central protrusion 154 of the flexible strip 146. Thispressure is transferred along the entire length of the flexible strip146 such that pressure is evenly distributed along the inner surface 148of the strip 146. In accordance with yet another embodiment, and withreference to FIG. 14, the inner surface 148 of the strip 146 may takethe form of a resilient tubular member 147 with additional compliance.By utilizing such a design, the interior volume 145 defined by the strip146 may be filled with viscoelastic materials enhancing the complianceof the strip 146 and the overall tissue ring interface.

In accordance with one aspect of the present invention, and withreference to FIGS. 15A, 15B, 16A and 16B, the ring 22 further comprisesa layer 40 of a relatively rigid material disposed on the dorsalperiphery of the ring 22. The layer 40, which may comprise a plastic ormetal alloy, prevents the exterior diameter D of the ring 22 fromchanging during adjustment of the tension element 32 to reduce theinternal diameter (or opening 37) of the ring 22. The layer 40, by itsstructural rigidity, imposes a circular arc shape for the entirety ofthe ring 22. Advantageously, the layer 40 allows the tension element 32to be adjusted following encapsulation of the ring 22 by fibrous tissueafter implantation, since adjustment of the internal diameter of thering 22 does not change the external diameter D of the ring 22.

The foregoing feature is illustrated in FIGS. 15A and 15B where the ring22 is shown in its fully opened and fully closed positions,respectively. As discussed above, the layer 40 forms a rigid skeletonthat permits the internal diameter of the ring 22 to change whilemaintaining the external diameter D constant. Radial movement of thetension element 32 is transmitted to the membrane 39 by the compressiblematerial 36. ePTFE is particularly well-suited for use as thecompressible material 36 because it can undergo a 3:1 reduction inlength without experiencing a significant increase in cross-section.

Accordingly, and as depicted in FIGS. 16A and 16B, increase or reductionof the effective length of the tension element 32 results in reversibleradial displacement at the internal periphery of the ring 22 oppositethe dorsal periphery. This in turn translates into a variation ofinternal diameter of the ring 22 from a fully open diameter to a fullyclosed diameter by expanding or controlling the ring 22 to control thetension applied by the ring 22 against a patient's body organ or duct.Preferably, the fully open internal diameter is about 35 mm, and thefully closed internal diameter is about 15 mm. More preferably, thefully open internal diameter is about 29 mm, and the fully closedinternal diameter is about 19 mm.

Referring now to FIG. 17, the tension element 32 in accordance with afirst embodiment is described. This tension element is disclosed indetail in U.S. Patent Application Publication No. 2005/0143766, which isincorporated herein by reference. Briefly, the tension element 32 hassufficient flexibility to permit it to be formed into the substantiallycircular shape of the ring 22, while also being able to transmit theforce necessary to adjust the ring diameter. The tension element 32therefore comprises a flexible core 41, preferably a metal alloy wire ofcircular cross section, on which is fixed, and wound coaxially, at leastone un-joined coil spring which defines the screw thread pitch.

As shown in FIG. 17, the tension element 32 preferably comprises twoun-joined coil springs that form a screw thread: a first spring 42,wound helicoidally along the flexible core 41, and a second spring 43 ofgreater exterior diameter. The second spring 43 preferably comprisescoils 44 of rectangular transverse section, so as to delineate a flatexternal generatrix. The first spring 42 is interposed between coils 44of the second spring 43 to define and maintain a substantially constantsquare screw thread pitch, even when the tension element 32 is subjectedto bending.

As a consequence of the foregoing arrangement, the ability of thetension element 32 to maintain a substantially constant thread pitch,when subjected to bending, confers great precision on adjustments of thering 22. This is especially so when it is realized that as the tensionelement 32 is drawn through the drive element 35, an ever-increasingcurvature is imposed on the remaining portion of the tension element 32.However, because the foregoing arrangement of un-joined coils maintainsa substantially constant screw thread pitch, the energy needed to drivethe drive element 35 remains low and the efficiency of energytransmission resulting from the use of a square screw thread pitchremains high. In addition, the use of a square screw thread pitchguarantees a stable adjustment position even when the drive element isunpowered.

Referring now to FIG. 18, the tension element 32 is described. The freeend 34 includes a crimped cap 45, the second spring 43 has coils with asquare transverse section, and the first spring 42 (not visible in FIG.18, but shown in FIG. 17) is intertwined between the coils of the secondspring 43. The flexible core 41 extends through the first and secondsprings 42, 43, and terminates close to the crimped cap 45. Inaccordance with one aspect of the present invention, the tension element32 further comprises a third spring 46 that is coupled to the flexiblecore 41, and the first and second springs 42, 43 at junction 47. Thethird spring 46 includes a loop 48 at the end opposite to junction 47,which permits the tension element 32 to be mounted to the first end 26of the ring 22.

With respect to FIG. 19, the tension element 32 is shown disposed withina skeleton 50 of the ring 22. The skeleton 50 includes a layer 51 thatforms the dorsal periphery (corresponding to the layer 40 of FIGS. 2A,2B, 16A and 16B), an anchor 52 that accepts the loop 48 of the tensionelement 32, and a drive element housing 53. The skeleton 50 ispreferably constructed from a high strength moldable plastic. As furtherdepicted in FIG. 19, the skeleton 50 extends along a greater arc lengththan the tension element 32. In accordance with another aspect of thepresent invention, the third spring 46 permits the gastric band 21 to bestraightened for insertion through a standard 18 mm trocar, despite thedifferential elongation of the skeleton 50 and the tension element 32.This feature is illustrated in FIG. 20, which depicts the ring 22inserted through 18 mm trocar 55 so that the ring 22 is substantiallystraight.

Referring now to FIG. 21, the housing 29 of the free end of the ring 22is described. The housing 29 comprises an elastomeric material, such assilicone, having a recessed portion 56, a tension element cavity 57 anda cable lumen 58. The recessed portion 56 is configured to accept thedrive element housing 53 of the skeleton 50, so that as the tensionelement 32 is drawn through the drive element 35 it extends into thetension element cavity 57. A cable lumen 58 extends through the housing29 so that the antenna cable 24 may be coupled to the drive element 35.The housing 29 preferably may be grasped in area G using atraumaticlaparoscopic graspers during manipulation of the gastric band 21.

In FIG. 22, the drive element housing 53 of the skeleton 50 is shownwith the drive element 35 and the tension element 32 disposedtherethrough. The antenna cable 24 is coupled to a motor (not shown)disposed within the drive element housing 53. The tension element 32 isin the fully opened (largest diameter) position, so that the crimped cap45 contacts the printed circuit board 59 of the reference positionswitch, described below with respect to FIG. 26.

Because the tension element 32 must be drawn through the drive element35 to cause tightening thereof, the tension element 32 described abovenecessarily requires that the tail end 34, that is, the end nearestcrimped cap 45, of the tension element 32 extends beyond the driveelement 35 with the extending portion increasing as the ring 22 istightened, making potential interference with the viscera possible. Inaddition, the tension element 32 may cause localized stress to theinside surface, for example, the compressible material 36, of thegastric band 21 as well as potentially to the viscera.

In accordance with an alternate embodiment and with reference to FIG.24, the diameter of the ring 22 is adjusted without the need for atension element including a tail end which is extended and retracted asthe need for adjustments in the diameter of the ring 22 are desired. Thetension element 32 in accordance with this embodiment is composed of aninner first strap member 440, an outer second strap member 442 and acamming strap member 444 moveably positioned therebetween. The firststrap member 440 includes an inner surface 446 and an outer surface 448,the second strap member 442 includes an inner surface 452 and an outersurface 454, and the camming strap member 444 includes an inner surface456 and an outer surface 458. The inner surface 446 of the first strapmember 440 is substantially smooth and is shaped and dimensioned forfacing the tissue which the ring 22 engages. The outer surface 448 ofthe first strap member 440 includes a plurality of recessed cammingsurfaces 460 shaped and dimensioned for interacting with protrudingcamming 462 surfaces extending from the inner surface 456 of the cammingstrap member 444. Similarly, the outer surface 454 of the second strapmember 442 is substantially smooth and is shaped and dimensioned forfacing the tissue which the ring 22 engages. The inner surface 452 ofthe second strap member 442 includes a plurality of recessed cammingsurfaces 464 shaped and dimensioned for interacting with protrudingcamming surfaces 466 extending from the outer surface 454 of the cammingstrap member 444.

As discussed above, the camming strap member 444 is shaped anddimensioned for positioning between the first strap member 440 and thesecond strap member 442 in manner such that the camming strap member 444is in sliding contact with the first and second strap members 440, 442but is free to move relative thereto. As such, when the camming strapmember 444 moves circumferentially relative to the first and secondstrap members 440, 442, the protruding camming surfaces 462, 466 of thecamming strap member 444 interact with the recessed camming surfaces460, 464 of the respective first and second strap members 440, 442. As aresult of this interaction, the first strap member 440 is caused to moveinwardly or outwardly selectively decreasing or increasing the effectivediameter of the ring 22.

Controlled movement of the camming strap member 444 is achieved by adrive element 470 secured at the first end 472 of the camming strapmember 444. In accordance with a preferred embodiment, the drive element470 is a conventional drive mechanism, for example, screw drive,friction belt drive, servomotor, etc.

It is further contemplated the recessed camming surfaces 460, 464 andthe protruding camming surface 462, 466 may be adjusted in height andlocation along the circumference of the tension element 32 so as toadjust the ability of the tension element 32 to control adjustments inthe diameter of the ring 22. That is, the total adjustment range of thetension element 32 will depend on the configuration of the recessed andprotruding camming surfaces 460, 462, 464, 466, specifically, the numberof camming surfaces and the height of the camming surface. In thesimplest case the adjustment diameters could be described as

θ_(i)=original diameter

h=height of wedge

θ_(f)=final diameter

θ_(f)=θ_(i)+2(h)

This tension element 32 construction offers a variety of advantages,including: the cost of the flexible spring assembly disclosed withreference to other embodiments can be avoided and the total throw of themotor can be reduced therefore reducing the length of the tail section.Multiple camming surface configurations can be adapted to the design toachieve different adjustment ranges while a constant pressure profile onthe restricted tissue can be is maintained.

Drive Element

With respect to FIGS. 25 and 26, the drive element 35 used inconjunction with the tension element 32 disclosed with reference toFIGS. 22 and 23, includes a motor 66 coupled to the antenna cable 24that drives the nut 60 through the gears 61. As with the variousembodiments presented throughout the present disclosure, the motor maytake a variety of forms including, but not limited to a stepper motorand piego motor. The nut 60 is supported by upper and lower bearings 62to minimize energy losses due to friction. The nut 60 is self-centering,self-guiding and provides high torque-to-axial force transfer. The driveelement 35 is disclosed in greater detail with reference to U.S. PatentApplication Publication No. 2005/0143766, entitled “TELEMETRICALLYCONTROLLED BAND FOR REGULATING FUNCTIONING OF A BODY ORGAN OR DUCT, ANDMETHODS OF MAKING, IMPLANTATION AND USE”, which is incorporated hereinby reference.

Referring now to FIG. 26, the reference position switch of the presentbanding system 1 is described. Because the drive element 35 of thepresent banding system 1 employs a nut 60 driven by a stepper motor 66,there is no need for the system to include a position sensor or encoderto determine the length of the tension element 32 drawn through thedrive element 35. Instead, the diameter of the ring 22 may be directlycomputed as a function of the screw thread pitch and the number ofrotations of the nut 60. To ensure an accurate calculation of the degreeof restriction imposed by the ring 22, however, it is desirable toprovide at least one reference point.

This reference datum is accomplished in the ring 22 of the presentinvention using a reference position switch that is activated when thering 22 is moved to its fully open position. The crimped cap 45 on thefree end of the tension element 32 serves this function by contactingelectrical traces 63 on the printed circuit board 59 (and also limitselongation of the screw thread). The circuit board 59 is disposed justabove the bearing 65, which forms part of the drive element 35 (see alsoFIG. 22). When the crimped cap 45 contacts the traces 63, it closes aswitch that signals the implantable controller that the ring 22 is inthe fully open position.

In accordance with an alternate embodiment, and with reference to FIG.27, a symmetrical drive system 170 is employed. Briefly, and inaccordance with a preferred embodiment of the present invention, thedrive system 170 employs two flexible members 172, 174 which, inaccordance with a preferred embodiment of the present invention, areflexible screws simultaneously operating upon the tension element 32using a single motor 176 with a dual actuated drive 178, 180. The dualactuated drives 178, 180 provide directional control for loosening ortightening the flexible members 172, 174. In accordance with a preferredembodiment of the present invention, the body of the tension element 32is constructed in substantially the same manner as that described withreference to the embodiment shown in FIGS. 17, 18 and 19. However, andconsidering the flexible members interact with the dual actuated drivesfor controlled construction and expansion of the ring 22, the body ofthe tension element may be constructed of various materials and may beconstructed without departing from the spirit of the present invention.However, and as will be appreciated based upon the following disclosure,flexible first and second screws 172, 174 are secured to the oppositeends 183, 194 of the tension element 32 allowing for actuation inaccordance with the embodiment disclosed herein.

By drawing the tension element 32 at both ends, and simultaneouslyapplying pressure to the opposite ends, the applied tension is uniformlydistributed along the length of the tension element 32.

More particularly, a flexible first screw 172 is provided at one end ofthe tension element 32. The first screw 172 includes a first end 182 anda second end 184. The first end 182 is secured to a first end 183 of thetension element 32 and the second end 184 is fed into a first actuateddrive 178 of the motor 176. Similarly, the flexible second screw 174includes a first end 186 and a second end 188. The first end 186 issecured to a second end 194 of the tension element 32 and the second end188 is fed into a second actuated drive 180 of the motor 176. With thefirst and second ends 183, 194 of the tension element 32 respectivelysecured to the first end 182 of the first screw 172 and the first end186 of the second screw 174, and the motor 176 connecting the secondends 184, 188 of the first and second screws 172, 174, a completecircular loop is created. The effective circumference of the circularloop is, therefore, readily adjusted by manipulating the extent to whichthe first and second screws 172, 174 are drawn into the first and secondactuated drives 178, 180 of the motor 176.

As briefly discussed above, the motor 176 is provided with first andsecond actuated drives 178, 180. The first and second actuated drives178, 180 include respective inputs 195, 196 that are positioned onopposites sides of the motor 176 for receiving the second ends 184, 188of the respective first and second screws 172, 174. As such, the secondend 184 of the first screw 172 is fed into the input 195 of the firstactuated drive 178 where it is engaged by a drive mechanism (forexample, a screw drive in accordance with a preferred embodiment of thepresent invention). The second end 188 of the second screw 174 is fedinto the input 196 of the second actuated drive 180 where it is engagedby a drive mechanism (for example, a screw drive in accordance with apreferred embodiment of the present invention).

In accordance with a preferred embodiment, the drive mechanisms of thefirst actuated drive 178 and the second actuated drive 180 employnut-like features upon which a threaded surface of the first and secondscrews 172, 174 ride so as to push or pull the first and second screws172, 174 through the motor body. When the motor 176 is energized, thefirst and second screws 172, 174 move in opposite directions and tightenthe tension element 32 about a central axis of the ring 22. Because bothscrews 172, 174 move at the same time, the tension element 32, andultimately, the gastric band 21, can be adjusted twice as fast as asingle direction screw with the same amount of work.

With the first screw 172 engaged by the drive mechanism of the firstactuated drive 178 and the second screw 174 engaged by the drivemechanism of the second actuated drive 180, actuation of the motor 176is controlled to actuate the first and second actuated drives 178, 180to either simultaneous draw the first and second screws 172, 174 intothe motor 176 or the simultaneous push the first and second screws 172,174 out of the motor 176 for either decreasing or increasing theeffective circumference of the tension element 32.

By employing the embodiment described above, symmetrical movement allowsfor a more uniform distribution of force on the tension element 32. Thetension element 32 is also fixedly secured to the ring 22 at an anchorpoint 175 diametrically opposite the motor 176. In this way, the firstand second screws 172, 174 connected to the tension element 32 pull themembrane 39 of the ring 22 uniformly inward or outward from the anchorpoint 175 diametrically opposite the motor 176 of the gastric band 21.It should be noted that is contemplated that the anchor point is notlimited to the top of the gastric band but may be located at one side oropposite the motor drive.

In accordance with an alternate embodiment as shown with reference toFIGS. 28 and 29, the drive system 170 includes a tension element 32composed of two flexible members (referred to as springs) 202, 204. Thesprings 202, 204 are linked together so as to define the tension element32 used in increasing or decreasing the circumference of the ring. Theflexible first member 202 is threaded externally like a bolt (innerspring) and the flexible second member 204 is internally threaded like anut (outer spring). The inner spring 202 is shaped and dimensioned toseat within the outer spring 204 in a manner coupling the inner andouter springs 202, 204 but allowing rotation of the outer spring 204relative to the inner spring 202 for controlled adjustment of theirrelative positions as discussed below in greater detail.

More particularly, the outer spring 204 is attached to a rotationalmotor 176 with the inner spring 202 threaded into the outer spring 204.As the motor 176 turns the inner spring 202 is either drawn into orpushed farther out of the outer spring 204 to either reduce or increasethe diameter of the stoma defined by the ring 22. To prevent totalrestriction of the stomach, the outer spring 204 or inner spring 202 isprovided with a hard stop 206 that will prevent further restriction. Itwill be appreciated that the inner and outer springs could also bethought of as a flexible screw and flexible nut.

Referring now to FIGS. 30 and 31, yet another embodiment is disclosed.In accordance with this embodiment, the tension element 32 mountedwithin the ring 22 is provided with a flexible hollow threaded shaft 208at its first end 26 and a flexible threaded shaft 210 at its oppositesecond end 28. The threaded shaft 210 is movably coupled to a drivemotor 176 secured at the free end 212 of the hollow threaded shaft 208for controlling movement of the first end 283 of the tension element 32relative to the second end 294 of the tension element 32.

More particularly, the hollow threaded shaft 208 defining the first end283 of the tension element 32 includes a free end 212 and a coupled end214, while the threaded shaft 210 defining the second end 194 of thetension element 32 includes a free end 216 and a coupled end 218. Thecoupled end 214 of the hollow threaded shaft 208 is secured to thecoupled end 218 of the threaded shaft 210.

A drive motor 176 is secured to the free end 212 of the hollow threadedshaft 208. The drive motor 176 includes an input passageway 220 shapedand dimensioned to guide the threaded shaft 210 therethrough and intothe cavity 222 defined by the hollow threaded shaft 208. As such, andwith the threaded shaft 210 engaged with the drive motor 176, the drivemotor 176 is actuated to either draw into or push threaded shaft 210 outof the hollow threaded shaft 208 to either reduce or increase thediameter of the stoma defined by the ring 22. To prevent excessiveinward or outward movement, it is contemplated the threaded shafts maybe provided with a hard stop(s) (not shown). Additionally, to facilitateconnection to the coupled end of the hollow shaft a tapered lead endfeature may be added to the free end of the threaded shaft. Similarly,it is further contemplated the hollow threaded shaft may have a conelike feature to more readily facilitate alignment to the threaded shaftduring connection.

In accordance with yet a further embodiment and with reference to FIGS.32 to 38, a quick connect coupling 224 for use in conjunction with ascrew drive mechanism 226 is employed. The quick connect coupling 224 isa snap-together feature molded into a central segment 228 of the ring22.

More particularly, the ring 22 contains the silicone sleeve thatinteracts with the patient's stomach to create the gastric band 21, butthe ring 22 is split at the central segment 228 to allow for controlledsplitting of the ring 22 in a manner allowing for ease of deployment andease of removal. As with the embodiments discussed above, a tensionelement 32 extends within the ring 22 and similarly includes a split inthe central segment 228. Accordingly, the ring 22 may be thought of asincluding a first segment 230 and a second segment 232. The firstsegment 230 includes a first end 234 and a second end 236 and the secondsegment 232 includes a first end 240 and a second end 242. The tensionelement 32 is similar composed of a first tension segment 244 and asecond tension segment 246. The first tension segment 244 includes afirst end 248 and a second end 250 and the second tension segment 246includes a first end 252 and second end 254. The first end 234 of thefirst segment 230 and the first end 240 of the second segment 238 arelinked at the motor 176 that couples the first end 248 of the firsttension segment 244 to the first end 252 of the second tension segment246. Completing the circle defined by the ring and tension elements 230,232, the second ends 236, 250 of the first segment 230 and first tensionsegment 244 and the second ends 242, 254 of the second segment 232 andsecond tension segment 246 are linked via the quick connect coupling224.

In practice, the gastric band 21, with the quick connect coupling 224disconnected allows the second ends 236, 242 of the first and secondsegments 230, 232 of the ring 22 to move freely relative to each other.Thus, the ring 22 can be positioned adjacent the stomach and the quickconnect coupling 224 is used by the surgeon to first place and attachthe gastric band 21 during surgery. The first end 248 of the firsttension segment 244 and the first end 252 the second tension segment 246each terminate with a drive screw 256. The drive screws 256 engage thedrive motor 176 and are actuated thereby. The motor 176 may then be usedto open and close the gastric band 21 about the stomach of the user.

It is contemplated the first and second tension segments 244, 246 couldbe made of braided cable, laminate polymers, or even a single wire. Thebody of the first and second tension segments 244, 246 may besubstantially wider than the drive screw 256 to uniformly distribute theload. The non-braided version will be more susceptible to fatigue andfailure so appropriate materials like nylon may need to be used. Asdiscussed herein in greater detail, the first and second tensionsegments 244, 246 are housed within a center molded cavity of thegastric band 21 that allows them to slip with respect to the gastricband 21 so that as they are tightened stress does not build up in thesilicone outer sleeve that would tend to wrinkle or fold the outermembrane.

With regard to the drive motor 176, it is housed within a pocket in themiddle of the gastric band 21 and is secured to the first end 234 of thefirst segment 230 of the ring 22. The motor housing 258 is grounded andattached to the housing sleeve 260 so that when energy or power isapplied; the motor shaft 262 rotates, not the motor housing 258. Themotor housing 258 is attached to a drive screw 267 that is coupled tothe opposite first ends 248, 252 of the first and second tensionsegments 244, 246. If one polarity is applied, the motor shaft 262rotates in a first direction and the system is tightened drawing thefirst ends 248, 252 of the respective first and second tension segments244, 246 toward one another. If the opposite polarity is applied, themotor shaft 262 rotates in a second direction opposite to the firstdirection and the system loosens, pushing the first ends 248, 252 of therespective first and second tension segments 244, 246 away from oneanother. The drive thread configuration can be changed to allow fordifferent speed or torque ratios of the motor to the linear travel ofthe screws. This will also prevent back travel when the motor is notenergized due to the inertia within the motor itself. Additionally, ifpower is always present, it is contemplated active braking could beincorporated by applying the same polarity to both poles of the motorthereby increasing its holding strength, although usage of power forbraking might not be practical in certain application as it wouldconsume power more quickly. It is further contemplated this could alsobe achieved passively by using a stepper motor which would inherentlybraking when power is removed.

In accordance with an alternate embodiment as shown with reference toFIG. 34, a tightening nut 261 is rotated around the outside of the firstand second tension segments 244, 246 and has a worm gear 263 coupled tothe motor (not shown). The worm gear 263 prevents back travel and forcescannot be passed from the tension segments 244, 246 back to the motor ifthe motor is not moving the disclosed worm gear configuration. Rotationin either direction by the motor drive shaft 265 linearly moves thescrew head ends 248′, 252′ of the first and second tension segments 244,246 towards each other or away from each other since the first andsecond tension segments 244, 246 are not actually rotated. It iscontemplated the threading on the ends of the first and second tensionsegments may not be circumferential but only on one side. This wouldimprove guidance and prevent slipping of the threads.

It is further contemplated the screw ends could be connected to drivecables forming the tension segments by crimping the metal thread end tothe drive cable, or it could be overmolded plastic if the resultingthreading was strong enough to work in conjunction with the drive. Itcould also be molded in the system as a hole with long fiber filleradded to the plastic to improve its tension capabilities.

Referring to FIG. 35, and in accordance with another drive structure foruse in accordance with the system described with reference to FIGS. 32and 33, a drive 266 with an angled beveled gearing surface is connectedto a motor 176 which is in turn connected to the outer portion of agastric band 21. In this configuration, angled racks 268, 270 are formedalong the first ends 248, 252 of the first and second tension segments244, 246 of the gastric band 21. As the motor 176 rotates, both ends248, 252 of the first and second tension segments 244, 246 of thegastric band 21 are drawn inward at the same speed if the motor 176 wereto rotate in a first direction, for example, counterclockwiseorientation, and the gastric band 21 is uniformly tightened.

With reference to FIG. 36, it is contemplated the beveled gearingsurface of the drive 266 may be oriented at a 90° angle from the aboveembodiment such that the angled racks 268, 270 are drawn over top of oneanother. The angled racks 268, 270 in these embodiments require a trackwith low friction by which they can travel linearly with respect to eachother. This track would also ensure that there is a solid connection tothe beveled gear and that no slippage occurs.

In accordance with an alternate embodiment, and with reference to FIG.37, the angled racks 268, 270 (shown above with reference to FIGS. 35and 36) are replaced by high strength cables 272, 273 and connecteddirectly around a motor shaft 269 in a manner similar to a winch system.The alternative could reduce the complexity of the design as the cableswould not require tight tolerances and there would be no concern thatthe racks could slip from the winch.

In accordance with yet another embodiment, and with reference to FIG.38, the motor 176 is external to the gastric band 21 and has a flexibledrive cable 274 that rotates any internal gears, racks, pinions, etc.(shown with reference to the drive of FIG. 33, although other drivesystems are contemplated). The drive cable 274 is capable of providingadequate torque to the drive screw 264 in order to tighten the gastricband 21. The flexible cable drive would be similar to that found on theJohnson & Johnson Mammotome™ MR product. This flexible drive cable couldbe implemented into several other embodiments as well when coupled withthe appropriate hardware at each of the ends.

While the drive element 35 of the present ring 22 is robust and notprone to failure, it may at times be necessary to release the tensionelement 32 in an emergency. The release of the tension element 32 wouldprovide for immediate release of tension applied by the ring 22 to thestomach and permit removal of the ring 22 from its position about thestomach.

In accordance with a first embodiment of a tension element releasesystem and with reference to FIGS. 39, 40 and 41, the tension element 32includes a free end 34 and a fixed end 33. The fixed end 33 is securedadjacent the first end 26 of the ring 22 via a release mechanism 312allowing selective release of the fixed end 33 of the tension element 32from the first end of the ring 22 for release of tension being appliedby the ring 22. The release mechanism 312 includes a jaw mechanism 314that selectively engages the fixed end 33 of the tension element 32. Thefixed end 33 is provided with a bulbous head 316 that is selectivelyseated within the jaw mechanism 314 in the manner discussed below ingreater detail.

The jaw mechanism 314 includes a fixed jaw member 318 and a movable jawmember 320. A jaw drive element 322 is positioned between the fixed jawmember 318 and the movable jaw member 320. The fixed jaw member 318 issubstantially L-shaped and includes a first leg 324 and a second leg 326oriented perpendicular to each other. Similarly, the movable jaw member320 is substantially L-shaped and includes a first leg 328 and a secondleg 330 oriented perpendicular to each other. The fixed jaw member 318and the movable jaw member 320 sit facing each other in a mirror likeorientation with the first legs 324, 328 of the respective fixed jawmember 318 and the movable jaw member 320 substantially parallel to eachother and the second legs 326, 330 of the respective fixed jaw member318 and the movable jaw member 320 facing each other in an alignedmanner. B_(y) adopting this orientation, the fixed jaw member 318 andthe movable jaw member 320 create a cavity in which the enlarged head316 of the tension element 32 may sit while the remainder of the tensionelement 32 extends through the opening 332 formed between the free ends334, 336 of the respective second legs 326, 330 of the fixed jaw member318 and movable jaw member 320. As will be appreciated based upon thefollowing disclosure, a spring 321 biases the movable jaw member 320toward the fixed jaw member 318 maintaining the free ends 334, 336 ofthe respective second legs 326, 330 of the fixed jaw member 318 andmovable jaw member 320 in proximity to each other for holding theenlarged head 316 of the tension element 32 until it is desired torelease the tension element 32.

When one desires to release the tension element 32, that is, release theenlarged head 316 of the tension element 32 from its position betweenthe fixed jaw member 318 and the movable jaw member 320, the jaw driveelement 322 is expanded in a manner pushing the movable jaw member 320away from the fixed jaw member 318. As the movable jaw member 320 ispushed away from the fixed jaw member 318, that is, as the jaw mechanism314 is moved from its locked orientation with the fixed jaw member 318and movable jaw member 320 in close proximity to its release orientationwith the fixed jaw member 318 and movable jaw member 320 moved away fromeach other, the opening 332 therebetween expands until it is larger thanthe enlarged head 316 of the tension element 32 at which time the fixedend 33 of the tension element 32 is released from its position betweenthe fixed jaw member 318 and the movable jaw member 320.

In accordance with a preferred embodiment, the jaw drive element 322 isa balloon 338 which may be selectively expanded for engagement with thefixed jaw member 318 and the movable jaw member 320 in a mannerselectively moving the fixed jaw member 318 and the movably jaw member320 to their release orientation. While a particular jaw drive element322 is disclosed above in accordance with a preferred embodiment of thepresent invention, it is contemplated other drive element mechanisms maybe employed without departing from the spirit of the present invention.

For example, and in accordance with an alternate embodiment shown withreference to FIGS. 42 and 43, the jaw drive element 322 might take theform of a balloon 338 secured to the fixed jaw member 318, which uponexpansion presses against the movable jaw member 320 to place the jawmechanism 314 in its release orientation. It is contemplated such aballoon 338 would be constructed of silicone and be supplied with fluidfor expansion via a catheter 339 extending along the present apparatus.

Another jaw drive element 322′ is shown with reference to FIGS. 44 and45. In accordance with this embodiment, a shape memory alloy spring 340is positioned between the fixed jaw member 318 and the movable jawmember 320. The spring 340 is linked to a source of electricity 342.Upon application of the a voltage across the spring 340, the spring 340will change shape, for example, and in accordance with a preferredembodiment, expand, forcing the fixed jaw member 318 and movable jawmembers 320 apart in a manner moving the jaw mechanism 314 to itsrelease orientation.

In accordance with an alternate embodiment as shown with reference toFIGS. 46-48, the jaw mechanism 314 includes a first movable jaw member320 a and a second movable jaw member 320 b. The first movable jawmember 320 a and the second movable jaw member 320 b are pivotallyconnected with first and second spring biasing members 344 a, 344 bforcing them toward one another. A jaw drive element 322 is positionedbetween the first movable jaw member 320 a and the second movable jawmember 320 b.

The first movable jaw member 320 a is substantially L-shaped andincludes a first leg 324 a and a second leg 326 a oriented perpendicularto each other. Similarly, the second movable jaw member 320 b issubstantially L-shaped and includes a first leg 324 b and a second leg326 b oriented perpendicular to each other. Each of the first and secondmovable jaw members 320 a, 320 b include a laterally extending flange346 a, 346 b through which a pivot pin 348 extends for pivotally linkingthe first movable jaw member 320 a to the second movable jaw member 320b in a manner described above. The first movable jaw member 320 a andthe second movable jaw member 320 b sit facing each other in a mirrorlike orientation with the first legs 324 a, 324 b of the respectivefirst and second movable jaw members 320 a, 320 b substantially parallelto each other and the second legs 326 a, 326 b of the respective firstand second movable jaw members 320 a, 320 b facing each other in analigned manner. By adopting this orientation, the first and secondmovable jaw members 320 a, 320 b create a cavity in which the enlargedhead 316 of the tension element 32 may sit while the remainder of thetension element 32 extends through the opening 332 formed between thefree ends 334, 336 of the respective second legs 326 a, 326 b of thefirst and second movable jaw members 320 a, 320 b. As will beappreciated based upon the following disclosure, the first and secondmovable jaw members 320 a, 320 b are biased toward each othermaintaining the free ends 334, 336 of the respective second legs 326 a,326 b of the first and second movable jaw member 320 a, 320 b inproximity to each other for holding the enlarged head 316 of the tensionelement 32 until it is desired to release the tension element 32. Whenone desires to release the tension element 32, that is, release theenlarged head 316 of the tension element 32 from its position betweenthe first and second movable jaw members 320 a, 320 b, the jaw driveelement 322 is expanded in a manner pushing the first and second movablejaw members 320 a, 320 b away from each other. As the first and secondmovable jaw members 320 a, 320 b are pushed away from each other, thatis, as the jaw mechanism 314 is moved from its locked orientation withthe first and second movable jaw members 320 a, 320 b in closeproximity, to its release orientation with the first and second movablejaw members 320 a, 320 b moved away from each other, the opening 332therebetween expands until it is larger than the enlarged head 316 ofthe tension element 32 at which time the fixed end 33 of the tensionelement 32 is released from its position between the first and secondmovable jaw members 320 a, 320 b.

As with embodiment described above, the jaw drive element 322 is aballoon 338 which may be selectively expanded for engagement with thefirst and second movable jaw members 320 a, 320 b in a mannerselectively moving the first and second movable jaw members 320 a, 320 bto their release orientation. While a particular jaw drive element isdisclosed above in accordance with a preferred embodiment of the presentinvention, it is contemplated other drive element mechanisms may beemployed without departing from the spirit of the present invention. Forexample, another jaw drive element 322′ is shown with reference to FIGS.49 and 50. In accordance with this embodiment a shape memory alloyspring 340 is positioned between the movable jaw members 320 a, 320 b.The spring 340 is linked to a source of electricity 342. Uponapplication of a voltage across the spring 340, the spring 340 willexpand forcing the movable jaw members 320 a, 320 b apart in a mannermoving the jaw mechanism 314 to its release orientation.

In accordance with yet another embodiment shown in FIGS. 51 and 52, thefixed end 33 of the tension element 32 is secured in position forselective release via a fracture mechanism 350. In particular, the fixedend 33 of the tension element 32 is secured to an elongated couplingelement 352 extending within a shape memory alloy tube 354, wherein uponthe application of a change in temperature, for example, and inaccordance with a preferred embodiment, heating, of the shape memoryalloy tube 354, the tube 354 will expand in a manner fracturing theelongated coupling element 352 and permitting release of the fixed end33 of the tension element 32.

The shape memory alloy tube 354 is substantially cylindrical andincludes a proximal end 356 and a distal end 358. The elongated couplingelement 352 is shaped and dimensioned to extend within the tube 354between the proximal end 356 and the distal end 358. The tube 354includes a first opening 360 at the proximal end 356 and a secondopening 362 at the distal end 358. The first opening 360 is slightlysmaller than the enlarged head 316 a of the coupling element 352 and theenlarged head 316 a is, therefore, shaped and dimensioned to sit uponthe ledge 357 defined by the first opening 360. The second opening 362of the tube 354 is slightly smaller than the first opening 360. However,the second end of the coupling element 352 also includes an enlargedhead 316 b which is shaped and dimensioned to sit upon the ledge 359defined by the second opening 362. As such, the coupling element 352 isheld between with first opening 360 of the tube 354 and the secondopening 362 of the tube 354 with the enlarged heads 316 a, 316 b of thecoupling element 352 sitting outside of the tube 354. The couplingelement 352 is provided with a reduced diameter fracture section 364located between the enlarged head 316 a at the first end of the couplingelement 352 and the enlarged head 316 b at the second end of thecoupling element 352. In accordance with a preferred embodiment of thepresent invention, the fracture section 364 is located adjacent thesecond end of the coupling element 352. The fixed end 33 of the tensionelement 32 is secured to the coupling element 352 at the second endthereof.

With this construction in mind, a heating coil 366 is positioned aboutthe shape memory alloy tube 354 for selective heating of the shapemember alloy tube 354 so as to cause expansion thereof. In practice,when it is desired to release the fixed end 33 of the tension element32, the heating coil 366 is supplied with current causing coil 366 toheat. The heat causes expansion of the shape memory alloy tube 354. Theexpansion of the shape memory alloy tube 354 results in the applicationof tension to the coupling element 352. The applied tension stretchesthe coupling element 352 along its length as enlarged heads 316 a and316 b are moved apart, which ultimately results in the fracture thereofat the weakened fracture section 364. Once the fracture section 364breaks, the second end of the coupling element 352 is free to fall awayfrom the tube 354 along with the fixed end 33 of the tension element 32.

It is also contemplated that cooling could be employed as a mechanismfor changing the shape of the elongated tube and the tube may be cooledthrough the use of a Peltier-cooling element positioned thereabout.

In accordance with a variation of the embodiment described above withreference to FIGS. 51 and 52, the tension element release system isadapted to allow for fluid filling of the gastric band 21 upon therelease of the tension element 32 or failure of the tension element 32.In accordance with such an embodiment as shown with reference to FIGS.53, 54 and 55, the ring 22 is provided with a secondary cavity 370 thatis placed in fluid communication with a fluid source 374 once thetension element is released. The secondary cavity 370 extends along thecircumference of the ring 22 and is adapted for filling thereof so as toapply pressure via the application of fluid pressure in manner similarto a conventional balloon based gastric band.

The secondary cavity 370 extends about the length of the ring 22 and thetension element 32 extends within (or adjacent to) the secondary cavity370 such that when the tension element 32 is release as described belowfluid access is provided to the secondary cavity 370 for the inflow offluid necessary to fill the secondary cavity 370 and maintain theapplication of pressure by the ring 22.

As with the embodiment described above with reference to FIGS. 51 and52, the fixed end 33 of the tension element 32 is secured in positionfor selective release via a fracture mechanism. In particular, the fixedend 33 of the tension element 32 is secured to an elongated couplingelement 352 extending within a shape memory alloy tube 354, wherein uponheating of the shape memory alloy tube 354, the tube 354 will expand ina manner fracturing the elongated coupling element 352 and permittingrelease of the fixed end 33 of the tension element 32.

The shape memory alloy tube 354 is substantially cylindrical andincludes a proximal end 356 and a distal end 358. The elongated couplingelement 352 is shaped and dimensioned to extend within the tube 354between the proximal end 356 and the distal end 358. The tube 354includes a first opening 360 at the proximal end 356 and a secondopening 362 at the distal end 358. The first opening 360 is slightlysmaller than the enlarged head 316 a of the coupling element 352 and theenlarged head 316 a is, therefore, shaped and dimensioned to sit uponthe ledge 357 defined by the first opening 360. The second opening 362of the tube 354 is slightly smaller than the first opening 360. However,the second end of the coupling element 352 also includes an enlargedhead 316 b which is shaped and dimensioned to sit upon the ledge 359defined by the second opening 362. As such, the coupling element 352 isheld between the first opening 360 of the tube 354 and the secondopening 362 of the tube 354 with the enlarged heads 316 a, 316 b of thecoupling element 352 sitting outside of the tube 354. The couplingelement 352 is provided with a reduced diameter fracture section 364located between the enlarged head 316 a at the first end of the couplingmember 352 and the enlarged head 316 b at the second end of the couplingmember 352. In accordance with a preferred embodiment of the presentinvention, the fracture section 364 is located adjacent the second endof the coupling element 352. The fixed end 33 of the tension element 32is secured to the coupling element 352 at the second end thereof.

With this construction in mind, a heating coil 366 is positioned aboutthe shape memory alloy tube 354 for selective heating of the shapemember alloy tube 354 so as to cause expansion thereof. When it isdesired to release the fixed end 33 of the tension element 32, theheating coil 366 is supplied with current causing the coil 366 to heat.The heat causes expansion of the shape memory alloy tube 354. Theexpansion of the shape memory alloy tube 354 results in the applicationof tension stretching the coupling element 352 along its length asenlarged heads 316 a and 316 b are moved apart which will ultimatelyresult in the fracture thereof at the weakened fracture section 364.Once the fracture section 364 breaks, the second end of the couplingelement 352 is free to fall away from the tube 354 along with the fixedend 33 of the tension element 32.

However, and in addition to the embodiment described above withreference to FIGS. 51 and 52, the coupling element 352 includes acentral port 372 connected to a remote fluid source 374 via port 377.The central port 372 extends from the first end of the coupling member352 to a stop point 375 adjacent the second end of the coupling member352, but beyond the fracture section 364. As such, when the fracturesection 364 is broken as described above, the fluid is free to flowthrough the coupling element 352, through the second opening 362 of thetube 354 and into the secondary cavity 370 for filling the secondarycavity 370 and supplying the ring 22 with a pressure source formaintaining the application of pressure against the stomach of the user.

Referring to FIGS. 56A, 56B and 56C, yet another embodiment ofimplementing a balloon based back-up system in conjunction with themechanical tension offered by the tension element 32 is disclosed. Inaccordance with such an embodiment, the fixed end 33 of the tensionelement 32 is secured to the second end 28 of the ring 22 via a releasemechanism 312 allowing selective release of the fixed end 33 of thetension element 32 from the second end 28 of the ring 22 for release oftension being applied by the ring 22. The release mechanism 312 includesa jaw mechanism 314 that selectively engages the fixed end 33 of thetension element 32. The fixed end 33 is provided with a bulbous head 316that is selectively seated within the jaw mechanism 314 in the mannerdiscussed below in greater detail.

The jaw mechanism 314 includes a fixed jaw member 318 and a movable jawmember 320. A jaw drive element 322 is positioned between the fixed jawmember 318 and the movable jaw member 320. The fixed jaw member 318 issubstantially L-shaped and includes a first leg 324 and a second leg 326oriented perpendicular to each other. Similarly, the movable jaw member320 is substantially L-shaped and includes a first leg 328 and a secondleg 330 oriented perpendicular to each other. The fixed jaw member 318and the movable jaw member 320 sit facing each other in a mirror likeorientation with the first legs 324, 328 of the respective fixed jawmember 318 and the movable jaw member 320 substantially parallel to eachother and the second legs 326, 330 of the respective fixed jaw member318 and the movable jaw member 320 facing each other in an alignedmanner. By adopting this orientation, the fixed jaw member 318 and themovable jaw member 320 create a cavity in which the enlarged head 316 ofthe tension element 32 may sit while the remainder of the tensionelement 32 extends through the opening 332 formed between the free endsof the respective second legs 326, 330 of the fixed jaw member 318 andmovable jaw member 320. As will be appreciated based upon the followingdisclosure, the movable jaw member 320 is biased toward the fixed jawmember 318 maintaining the free ends forming an opening 332 between thefixed jaw member 318 and movable jaw members 320 in proximity to eachother for holding the enlarged head 316 of the tension element 32 untilit is desired to release the tension element 32.

When one desires to release the tension element 32, that is, release theenlarged head 316 of the tension element 32 from its position betweenthe fixed jaw member 318 and the movable jaw member 320, the jaw driveelement 322 is expanded in a manner pushing the movable jaw member 320away from the fixed jaw member 318. As the movable jaw member 320 ispushed away from the fixed jaw member 318, that is, as the jaw mechanism314 is moved from its locked orientation with the fixed jaw member 318and movable jaw member 320 in close proximity, to its releaseorientation with the fixed jaw member 318 and movable jaw members 320moved away from each other, the opening 332 therebetween expands untilit is larger than the enlarged head 316 of the tension element 32 atwhich time the fixed end 33 of the tension element 32 is released fromits position between the fixed jaw member 318 and the movable jaw member320.

In accordance with a preferred embodiment, the jaw drive element 322 isa balloon 338 which may be selectively expanded for engagement with thejaw members 318, 320 in a manner selectively moving the jaw members 318,320 to their release orientation. As will be appreciated with thefollowing disclosure, the proximal end of the jaw mechanism 314 wherethe balloon 338 is position is in fluid communication with a fluidsource 374 via a port 377 and the balloon 338 is oriented along the jawmechanism 314 so as to block the flow of fluid until it is desired. Whenthe balloon 338 is fully expanded for release of the fixed end 33 of thetension element 32 as described above, a needle 376 fixed relative toand extending through the movable jaw member 320 contacts the balloon338 to rupture the balloon 338. With the rupturing of the balloon 338, apassageway 378 is formed between the remote fluid source 374 and thecavity formed between the fixed jaw member 318 and the movable jawmembers 320. The remote fluid source 374 is in fluid communication withthe passageway 378 and fluid is free to flow through the jaw mechanism314 and into the secondary cavity 370 (see FIGS. 53, 54 and 55) forfilling the secondary cavity 370 and supplying the ring 22 with apressure source for maintaining the application of pressure against thestomach of the user.

As discussed above with regard to the embodiments in FIGS. 53, 54 and55, a fluid source 374 is required for implementation of the embodiment.This fluid source 374 is preferably incorporated into theantenna/controller pod 23. In order to ensure fluid pressure is notapplied in an undesirable manner, the fluid source 374 is provided witha fail-safe mechanism for releasing fluid pressure in the event of amalfunction of the tension element and when desired by the operator asdiscussed below with regard to FIGS. 59-67.

In accordance with a variation on this embodiment, the rupture of theballoon 338 could allow for the release of fluid from the ring 22facilitating release thereof in conjunction with the release of thetension element 32. This would occur where the fluid source (or in thisvariation, the fluid reservoir) 374 is empty and the fluid is allowed toflow from a prefilled secondary cavity 370 and to the fluid reservoir374 rather than the fluid flowing form the fluid source 374 to thesecondary cavity 370.

In accordance with an alternate embodiment, and with reference to FIGS.57A, 57B, 58A and 58B, the flow of fluid from the cavity 370 to thefluid source (or reservoir) 374 may be controlled by an electricallysensitive membrane 375 that is destroyed upon the application of theelectricity. Once destroyed the passageway between the fluid reservoir374 and the cavity 370 of the ring 22 is open allowing for the free flowof fluid.

In accordance with the concept of allowing for the release of fluid heldin the secondary cavity 370 of the ring 22, the fluid reservoir 374could be an expandable reservoir that expands or contracts to controlthe volume of fluid (and as such the pressure applied by the ring).Expansion or contraction of the fluid reservoir 374 is controlled by ashape memory alloy actuator 377 that expands or contracts the fluidreservoir 374 based upon the application of electricity (and ultimatelythe generation of heat therein) thereto via electrical leads 379.Because the fluid reservoir 374 will be in a vacuum relationship withthe cavity 370, controlled expansion and contraction of the fluidreservoir 374 will cause fluid to be drawn from or forced into thecavity 370 of the ring 22.

In accordance with an embodiment shown in FIGS. 59, 60 and 61, a fluidsource valve 380 is provided along the fluid path to the ring 22. Thefluid source valve 380 includes a first chamber 382 in communicationwith an upstream portion of the fluid source 374 via an inlet 384. Thefluid source valve 380 includes a second chamber 386 separated from thefirst chamber 382 by a valve release membrane 388 formed in a septum 390separating the first chamber 382 from the second chamber 386. The secondchamber 386 includes an outlet 392 leading to a catheter 394 linking thefluid source to the ring 22. When it is desired to allow for the flow offluid to the ring 22, electrical energy as applied to the valve releasemembrane 388 destroying the valve release membrane 388 and allowingfluid to freely flow from the inlet 384, through the first chamber 382,the valve release opening 389 and the second chamber 386, and into theoutlet 392 for flow though the catheter 394 and into the ring 22.

In accordance with an alternate embodiment, and with reference to FIGS.62, 63 and 64, the fluid source valve 380 includes a first chamber 382in communication with an upstream portion of the fluid source 374 via aninlet 384. The fluid source valve 380 includes a second chamber 386separated from the first chamber 382 by a valve release opening 389formed in a septum 390 separating the first chamber 382 from the secondchamber 386 and in which a resilient plug 400 is positioned. The plug400 is held in position by upper and lower resilient lips 403 a and 403b respectively biasing the plug 400 with the valve release opening 389in septum 390. The second chamber 386 includes an outlet 392 leading toa catheter 394 linking the fluid source 374 to the ring 22. When it isdesired to allow for the flow of fluid to the ring 22, an operator mayapply pressure through the skin of a patient to access a flexible upperwall 404 of the first chamber 382 and push the plug 400 from itsposition within the valve release opening 389 and allow fluid to freelyflow from the inlet 384, through the first chamber 382, the valverelease opening 389 and the second chamber 386, and into the outlet 392for flow though the catheter 394 and into the ring 22.

In accordance with yet another alternate embodiment, and with referenceto FIGS. 65, 66 and 67, the fluid source valve 380 includes a firstchamber 382 in communication with an upstream portion of the fluidsource 374 via an inlet 384. The fluid source valve 380 includes asecond chamber 386 separated from the first chamber 382 by a valverelease opening 389 formed in a wall or septum 390 separating the firstchamber 382 from the second chamber 386. A ball 406 is positioned in thesecond chamber 386 and held in valve release opening 389 by a springmember 402 biasing the ball 406 toward the first chamber 382 andplugging the valve release opening 389. The second chamber 386 includesan outlet 392 leading to a catheter 394 linking the fluid source 374 tothe ring 22. When it is desired to allow for the flow of fluid to thering 22, an operator may apply pressure through the skin of a patient toaccess a flexible wall 407 of the second chamber 386 and push the spring402 in a manner releasing the ball 406 from its position within thevalve release opening 389 and allowing fluid to freely flow from theinlet 384, through the first chamber 382, the valve release opening 389and the second chamber 386, and into the outlet 392 for flow though thecatheter 394 and into the ring 22.

In accordance with alternate embodiments as shown with reference toFIGS. 68 and 69, the fixed end 33 of the tension element 32, that is theportion of the tension element 32 secured to the ring 22 such thataction of the drive element 35 causes enlargement or reduction in theeffective diameter of the tension element 32, is selectively releasedvia a selective connection mechanism. In accordance with a firstembodiment as shown with reference to FIG. 68, actuation of a pin 1114(whether it be by way of shrinking or removal) allows for movement offirst and second detent balls 1116, 1118 permitting release of aconnection 1120 linking the fixed end 33 of the tension element 32 tothe ring 22.

In particular, the fixed end 33 of the tension element 32 is securelyheld in position relative to the ring 22 based upon the interference fitcreated between a retaining disk 1121 including a circumferential recess1125 formed along the inner wall thereof, the first and second detentballs 1116, 1118, the pin 1114 and the connection 1120. With the variouscomponents held as shown in FIGS. 68 and 69, the connection 1120 isfixedly held relative to the retaining disk 1121 which is secured to thering 22. Once the pin 1114 is removed from its position forcing thedetent balls 1116, 1118 into the circumferential recess 1125 and sittingwithin a central cavity 1127 of the connection 1120, the detent balls1116, 1118 will move centrally (as a result of the tension applied bythe tension element 32) and the fixed end 33 of the tension element willbe free to move since the interference fit will have been broken.

Referring to FIG. 69, movement of the detent balls 1116, 1118 is furtherfacilitated by the provision of springs 1123 which encourage the detentballs 1116, 1118 to move centrally upon the removal of the pin 1114.

As discussed above, removal of the pin is achieved either physically orby way of shrinking. Where it is desired to shrink the pin 1114, the pin1114 is preferably composed of a shape memory alloy adapted to shrinksufficiently upon the application of heat to allow for the movement ofthe detent balls 1116, 1118 from their positioned within thecircumferential recess 1125. In accordance with such and embodiment, aheater mechanism composed of a resistive wire (not shown) is coiledabout the shape memory alloy pin 1114. The heating coil uses RF energytransferred to the pin 1114 by means of an inductive coupling realizedbetween the antenna/controller pod 23 and an external RF emitter.

Alternately, it is contemplated the pin may be constructed for simplysliding from its position within the central cavity of the connection.In accordance with another embodiment, the pin may be an electroactivated polymer based drive element which shrinks by means of anapplied voltage and/or current induced in the pin by means of aninductive coupling.

In accordance with a third embodiment as shown with reference to FIGS.70 and 71, the fixed end 33 of the tension element 32 is selectivelysecured to the ring 22 by way of a retaining pin 1212. The retaining pin1212 is fixedly mounted within the ring 22 and engages an aperture 1213formed in the tension element 32. The retaining pin 1212 is actuated viaa mechanically amplified retractable pin assembly 1210. The pin assembly1210 is secured to the ring 22 and triggered by the motion of a shapememory drive element or a piezoelectric drive element 1226. Themechanically amplified retractable pin assembly 1210 allows the motionnecessary for activating the moving retaining pin 1212 to be extremelysmall (for example, in the hundreds of a micrometer range). The reducedmotion is achieved by means of shape memory alloy or piezoelectric baseddrive elements.

The embodiment includes a housing 1228 secured to the ring 22 and inwhich a spring biased retaining pin 1212 is mounted for movement betweena lock positioned and a release position. The retaining pin 1212includes an output pin 1230 shaped and dimensioned for seating within anaperture 1213 formed at the end of the tension element 32. The retainingpin 1212 further includes a spring flange 1232 which is acted upon by adrive spring 1234 when the shape memory alloy drive element (such asnitinol) 1226 permits movement thereof. More particularly, controlledmovement of the retaining pin 1214 is achieved by creating aninterference fit between the retaining pin 1214 and the shape memoryalloy drive element 1226 by positioning first and second detent balls1216, 1218 between the pin 1214 and the drive element 1226. The driveelement 1226 includes a drive element body 1236 having an hourglassshape and moves between a first position (see FIG. 70) and secondposition (see FIG. 71). When the drive element body 1236 is in its firstposition, the detent balls 1116, 1118 are forced into an interferenceposition preventing movement of the pin 1114 (see FIG. 70). However,when the drive element 1226 is heated it breaks a coupling linking it tothe base of the housing 1228 and is free to move upwardly under the biasprovided by spring 1237 (see FIG. 71). When the drive element 1226 movesupwardly in this manner, the detent balls 1216, 1218 are free to moveinto the narrow section of the drive element body 1236 allowing thedetent balls 1216, 1218 to move from their position interfering withmovement of the pin 1214. Thereafter, the drive spring 1234 moves thepin 1214 to its release position disconnecting the retaining pin 1214,in particular, the output pin 1230, from engagement with the tensionelement 32.

In summary, the mechanically amplified retractable pin assembly 1210employs a shape memory alloy drive element 1226 for triggering energyrelease stored in a loaded compression drive spring 1234. When in theextended position as shown with reference to FIG. 70, the pin 1214 isseen to be loaded by the compression drive spring 1234. The drive spring1234 remains firmly locked in this position due to the ball lock show inFIG. 70. This is mad possible by the drive element body 1236 whichdrives outwardly an array of detent balls 1216, 1218. Once actuatedhowever, the spring 1237 drives shape memory alloy drive element drives1226 upwardly thereby causing the detent balls 1216, 1218 to rollinwardly and allowing the pin 1214 to retract under the force of thedrive spring 1234.

Under certain circumstances it may become necessary to release thetension element 32 for emergency removal of the ring 22 from itsposition around the stomach. As such, and in accordance with a firstembodiment as shown with reference to FIGS. 73, 74, 75 and 76, the ring22, and in particular, the tension element 32, is provided with arelease pin 512 that allows for release of the free end 34 of thetension element 32 from its secure attachment position relative to thering 22. The release pin 512 transversely extends through the ring 22 ata position adjacent to the fixed end 33 of the tension element 32. As aresult, when the release pin 512 extends through the ring 22 and is inengagement with the fixed end 33 of the tension element 32, the tensionelement 32 is securely held in position for contraction and expansion ofthe ring 22 as discussed herein. However, when the release pin 512 ispulled from its position along the ring 22 and out of engagement withthe fixed end 33 of the tension element 32, the fixed end 33 of thetension element 32 is released for free movement within the ring 22 (seeFIGS. 74 and 76). As such, the tension created between the free end 34of the tension element 32 and the fixed end 33 of the tension element32, which ultimately allows for a reduction in the effective size of thering 22, is released and the ring 22 is allowed to return to itsunbiased large diameter configuration. Once in this large diameterconfiguration, the ring 22 may be readily removed from its positionabout the stomach of the patient.

In accordance with an alternate embodiment, and with reference to FIGS.77 and 78, the nut 60 of the drive element 35 is replaced with a slipnut 60 that allows for selective release of the free end 34 of thetension element 32 from its position within the drive element 35. Moreparticularly, the slip nut 60 allows the threaded free end 34 of thetension element 32 to slip past the drive nut 60 when necessary to allowthe band restriction to be released if the motor 66 fails to operate.The slip nut 60 has the advantage of being either spring 103 loaded torelease at a known pull force of the threaded screw (see FIG. 77) or theslip nut 60 could be normally closed and a linkage 63 is provided thatcould be activated at the antenna/controller pod 23 (see FIG. 78).

Referring now to the embodiment presented with reference to FIG. 77, thenut 60 is spring-loaded for release of the threaded free end 34 of thetension element 32 at a known pull force. More specifically, a slip nut60 is a nut formed in multiple pieces which are held together viasprings or other means. FIG. 77 shows the slip nut 60 spring loaded toopen at a desired pull force on the threaded free end 34 of the tensionelement 32. Springs by design provide force greater than the forcesgenerated under normal conditions when food is swallowed, but if theband is stretched circumferentially by using an esophageal dilator theforce overcomes the springs and the threaded free end 34 slips throughthe nut 60 relaxing the restriction. FIG. 78 shows the slip nut 60wherein multiple pieces are held together with a linkage 63 thatterminates in the antenna/controller pod 23 for disengaging the nut 60from the threaded free end 34. The termination of the linkage 63 couldbe activated by a simple toggle 516. FIG. 79 shows this toggle 516 andalso provides a sketch of the linkage termination. The simple push pulldesign allows a doctor to make an incision in the skin to access thetoggle 516. A further improvement would be to provide a button, or somemeans of activating the linkage without cutting the skin to access therelease mechanism. In implementing such an embodiment, it iscontemplated the button would be spring loaded such that upon access tothe button with, for example, a hypodermic needle, pushing the buttonreleases the spring and thereby activates the linkage release mechanism.

With reference to the embodiment shown in FIG. 79, the split nut 60 isactivated for release through actuation of a button 518 at theantenna/controller pod 23. This embodiment overcomes the need for accessinto the patient's abdomen and could be activated without the need forincisions. If an emergency situation presented itself the patient couldhave a small incision made above the antenna/controller pod 23 on thesternum and the fail-safe linkage 63 could be activated directly. Thiswould allow the device to be replaced at a later date, or troubleshootthe device and possibly replace the antenna/controller pod 23 in asubcutaneous procedure without needing to remove the entire implant.

Another embodiment for the release of the threaded free end 34 of thetension element 32 is shown with reference to FIGS. 80 and 81. Thisembodiment includes a nut 60 construction that improves upon the nut'sability to engage and disengage simply. The use of an elliptical nut 60that pivots on an axis perpendicular to the axis of the threaded freeend 34 of the tension element 32 allows for easy engagement anddisengagement of the threaded free end 34 of the tension element 32.This embodiment also utilizes a linkage 63 from the antenna/controllerpod 23 and a switch/toggle 516 to pull the threaded free end 34 of thetension element 32 for disengagement. The nut 60 is spring loaded viaspring 517 to provide positive displacement for the nut 60 to engage thethreads of the threaded free end 34 of the tension element 32 when thefail-safe is not engaged. FIG. 80 shows the elliptical nut 60 in theengaged position and FIG. 81 shows the elliptical nut 60 in thefail-safe disengaged position. In FIG. 81, the linkage wire 63 that isconnected to the antenna/controller pod 23 is moved to a position forfail-safe release of the threaded free end 34 of the tension element 32,which causes the elliptical nut 60 to move and release from the threadedfree end 34.

In accordance with yet another embodiment as shown with reference toFIG. 82, an antenna/controller pod 23 that utilizes a magneticdeactivation function is disclosed. This requires a magnetic coil ormagnetic emitting antenna 522 to be placed over the antenna 83 of theantenna/controller pod 23 and the oscillating electromagnetic fielddeactivates the device electronically. That is, the magnetic fieldinduces a reverse polarity in the antenna/controller pod 23, which inturn reverses the voltage sent to the motor 66. This back drives themotor 66 without the use of the control pod in case of an electricalfailure in the controller pod, but the motor was still operable. Thecontroller pod would have a secondary circuit to allow the oscillatingmagnetic field coupling to generate a sufficient amount of power todrive the motor in a given direction. In this case, the desire would beto rotate the motor such that the pressure around the tissue isrelieved. MRI sensitivity should not be an issue as an MRI generates avery high intensity permanent field (which will not generate a voltagein a magnetic coil or magnetic emitting antenna) and a very lowintensity oscillating electromagnetic field (which will not generate asignificant voltage since it is low intensity). The technical challengesof providing enough energy to the implant to reverse the voltage to themotor 66 is also challenged if the wires from the antenna/controller pod23 becomes detached from the motor 66 or antenna/controller pod 23itself. FIG. 82 shows the magnet over the antenna 83 providing energy toreverse the motor 66.

Referring now to other embodiments for release of the threaded free end34 of the tension element 32. In FIGS. 83, 84 and 85, the drive nut 60has a split construction and is composed of four distinct elements 560a, 560 b, 560 c, 560 d forming a central aperture 524 through which thethreaded free end 34 of the tension element 32 passes for threadeddriving as discussed above. A driving gear 526 is secured to the outersurface 528 of the nut 60 and drives it in a circular configuration asdescribed above. However, the drive nut 60 is resilient and is adaptedfor biasing such that the threads 530 formed along the inner surface ofthe nut 60 disengage from threads 532 formed along the external surface534 of the free end 34 of the tension element 32. In particular, each ofthe nut elements 560 a-d making up the nut 60 has a C-shaped crosssectional profile as shown with reference to FIGS. 83 and 85. TheC-shaped profile includes a first plate member 536 and a second platemember 538 connected by a central connecting member 540. The centralconnecting member 540 also functions as a part of the inner surface 542of the aperture 524 through which the fixed end 33 of the tensionelement 32 passes. The connecting member 540 is provided with a weakenedportion 544. As such, when pressure is applied to the first plate member536 in a direction toward the second plate member 538, the first platemember 536 will then move downwardly toward the second plate member 538causing the connecting member 540 to move from its normal orientationrelative to the second plate member 538 and form an acute angularrelationship with respect to the second plate member 538. By applyingpressure to all of the first plate members 536 of the respective nutelements 560 a-d simultaneously, the inner threads 530 along the nut 60are moved away from the free end 34 of the tension element 32 therebyproviding for release and free movement of the tension element 32relative to the nut 60.

In accordance with a preferred embodiment, pressure is applied to thefirst plate member 536 of the respective nut elements 560 a-d throughthe utilization of a plurality of pressure application plates 546. Eachof these pressure application plates 546 includes a resilient balloon548 which may be expanded upon application of fluid pressure thereto.Since the pressure application plates 546 are formed so as to bepositioned directly adjacent the first plate members 536 of therespective nut elements 560 a-d, when a balloon 548 is expanded, theballoon 548 will expand into contact with the first plate member 536 ofthe nut element 560 a-d pushing it toward the second plate member 538 ofthe nut element 560 a-d and causing the connecting member 540 to angleaway from the free end 34 of the tension element 32 as described above.

In accordance with yet another embodiment of the present invention, andwith reference to FIGS. 86, 87 and 88, the nut 60 is provided withflanges 550 upon which the internal threading 530 of the aperture 554 ispositioned. These flanges 550 are secured to the nut 60 for controlledmovement relative thereto. In particular, and with reference to FIG. 86,when the nut 60 and in particular, the flanges 550, are intended forengagement with threading 530 formed along the outer surface 534 at thefree end 34 of the tension element 32, the flanges 550 are orientedsubstantially normal to the plane in which the nut 60 lies. As such, andwhen in this configuration, the internal threading 552 along the flanges550 engages the threading 532 at the free end 34 of the tension element32 and rotation of the nut 60 causes the threaded free end 34 to bemoved relative to the nut 60 for drawing the tension element 32 throughthe nut 60.

However, the rear outer surface 556 of each flange 550 is provided witha resistive heating element 558 that is connected to an electrical coil560 secured along the back surface 562 of the outer periphery 564 of thenut 60. As such, when electricity is applied to the coils 560, theresistive heaters 558 are actuated heating the flanges 550. The flanges550 are constructed such that when they are heated, or otherwiseencounter a change in temperature, they will bend away from the free end34 of the tension element 32 forming an acute angle with the plane inwhich the nut 60 lies (see FIG. 88). Once in this configuration, andwith reference to FIG. 88, the free end 34 of the tension element 32 isfree to move relative to the nut 60 for free movement of the tensionelement 32 relative thereto.

Referring now to FIGS. 89, 90 and 91, yet another embodiment for releaseof the tension element 32 is disclosed. In accordance with thisembodiment, the fixed end 33 of the tension element 32 is secured to atwo-bar linkage 566. When the tension element 32 is intended forutilization in constriction of the stomach, the two-bar linkage 566 isfolded so that the links 568, 570 nearly overlap (see FIG. 89). When theband 21 needs to be released in an emergency, the two-bar linkage 566 isactuated via a pull lever 567 (see FIG. 91) so as to pull the two barlinkage 566 from its folded configuration and into an extendedconfiguration (see FIG. 90). With the two bar linkage 566 in an extendedconfiguration, the effective length of the tension element 32 isincreased providing additional diameter within the ring 22 and allowingthe gastric band 21 to be moved from its position along the stomach.

Referring now to FIGS. 92, 93 and 94, a compression, friction driveassembly 572 is utilized for pulling the tension element 32. Thefriction drive assembly 572, however, includes a release member 574which moves the opposed rollers 576, 578 of the friction drive assembly572 apart from each other allowing for free movement of the tensionelement 32 within the ring 22. Controlled movement of the release member574 is achieved via the utilization of a pull wire 580 which, when actedupon, forces the rollers 576, 578 of the friction drive assembly 572apart against the bias of the spring 577 that biases them toward thetension element 32, permitting free movement of the tension element 32.In accordance with a preferred embodiment, and with reference to FIG.94, movement of the wire 580 is controlled by a screw mechanism 579 thatmay be selectively acted upon with, for example, a hex wrench 581, toloosen or tighten the wire 580.

In accordance with yet another embodiment of the present invention, andwith reference to FIG. 95, the antenna/controller pod 23 is providedwith an access port 582 providing a medical practitioner with access tothe control electronics of the antenna/controller pod 23 for controlthereof in the event of failure. In accordance with such an embodiment aneedle 584 would access the access port 582 so as to act like a contactthat would either flex contacts 586, 588 or just bridge the contacts586, 588 to run the motor 66 in the direction to open the gastric band21 to a maximum diameter thereby relieving any pressure applied by thegastric band 21. For such a method to work, the antenna/controller pod23 is provided with a battery 590 having a shelf life, for example, often or more years, and with enough power to store energy to power thegastric band 21 for a reasonable length of time. Since there is abattery 590 provided with the antenna/controller pod 23, telemetry couldbe used via wireless technology such as Bluetooth and could allow apatient to self adjust the gastric band 21 without the need for a powermodule. It is further contemplated rechargeable batteries may beemployed and recharging may be achieved on a regular basis via a powerunit at a doctor's office or while the patient is sleeping so that morebenefits could come from the ability to non-invasively adjust the band.

In accordance with a variation on the embodiment disclosed withreference to FIG. 95, the antenna/controller pod 23 is provided withdual access ports 582 a, 582 b linked to the printed circuit band 583.As such, and when emergency situations arise under circumstances wherethe antenna/controller pod 23 does not have sufficient power, the twoneedles 584 a, 584 b applied to the first and second ports 582 a, 582 bof the antenna/controller pod 23 are charged to supply power to theantenna/controller pod 23. In accordance with this embodiment, the firstand second ports 582 a, 582 b are provided with self-healing elastomerictargets 592 a, 592 b for needle placement.

As briefly discussed above, the needles 584 a, 584 b are charged. Assuch, the needles 584 a, 584 b are connected to a power source 594 thatis readily available in a hospital. When the needles 584 a, 584 b arecontacting the conductors 586, 588 in the printed circuit board 583 ofthe antenna/controller pod 23, the motor 66 will run in the openingdirection and the diameter of the gastric band 21 is increased toeliminate any pressure applied by the gastric band 21.

The gastric band 21 would then return to normal operating conditionswhen appropriate and can be used as designed in accordance with theprinciples of the present invention. The present embodiment would alsofunction for its intended purpose in the event the printed circuit boardfailed provided the emergency electrical path employed in accordancewith this embodiment is not part of the operating circuitry of theprinted circuit board.

Ring Closure System

With respect to FIGS. 97A and 97B, a preferred embodiment of the clip 27for securing the gastric band 21 in the closed position is described.The clip 27 on the first end 26 of the ring 22 includes an aperture 70,a tab 71 having a hinge 72 and a slot 73. The aperture 70 is dimensionedto accept the second end 28 therethrough, while the slot 73 isdimensioned to accept the flange 74 disposed on the second end 28.

To close the ring 22, the clip 27 is grasped by the tab 71 and the tag25 of the antenna/controller pod 23 (see FIG. 1) is inserted through theaperture 70. The clip 27 is then pulled toward the second end 28 so thatthe housing 29 passes through the aperture 70 while the housing 29 isgrasped with atraumatic forceps; the conical shape of the housing 29facilitates this action. Force is applied to the tab 71 until the slot73 captures the flange 74, thereby securing the ring 22 in the closedposition. The physician may subsequently choose to disengage the slot 73from the flange 74 by manipulating the tab 71 using laparoscopicforceps, for example, to reposition the ring 22. Advantageously,however, forces inadvertently applied to the tab 71 in an oppositedirection will cause the tab 71 to buckle at the hinge 72, but will notcause the flange 74 to exit the slot 73. Accordingly, the hinge 72 ofthe tab 71 prevents accidental opening of the clip 27 when the tab 71 issubjected to forces that cause the tab 71 to fold backwards away fromthe housing 29, such as may arise due to movement of the patient, theorgan, of or bolus of fluid passing through the organ.

As discussed above, it may at times become necessary to release thepressure applied by the gastric band 21. With this in mind, and inaccordance with yet another embodiment as shown with reference to FIGS.98 and 99, the first and second ends 26, 28 of the gastric band 21 areprovided with a mechanism allowing release from their locked positionsvia a remote latch unlock mechanism 1310. In particular, the clip 27holding the first and second ends 26, 28 of the gastric band 21 togetheris released via a variety of electromechanical mechanisms. For example,actuation of an emergency release button (not shown) on theantenna/controller pod 23 will cause release of the clip 27. When thebutton triggers a communication, a voltage is applied on a flangeactuator 1314 by the electronics of the antenna/controller pod 23. Thetemperature of the actuator 1314 then increases and this triggersmovement of the flange 74 toward the inside of the gastric band 21 untilthe band clip 27 is released (for example, via a shape memory alloyactuator or a bimetallic actuator). Such an embodiment, might allow fortreatment without the patient visiting the hospital or other treatmentcenter. The unit might be activated via modem or Internet connection bythe surgeon.

Antenna/Controller Pod

With respect to FIGS. 100 and 101, the antenna/controller pod 23 of thepresent banding system is described. The antenna/controller pod 23 isdisposed at the distal end of the antenna cable 24 and includes theremovable tag 25 and holes 75. The tag 25 comprises a grip structurethat facilitates manipulation and placement of the antenna/controllerpod 23 during implantation; after which the tag 25 is removed using ascissors cut. The tag 25 also includes hole 25 b that allows the use ofa suture thread to assist in passing the antenna/controller pod 23behind the stomach. The holes 75 also are dimensioned to be compatiblewith standard suture needles from size 1-0 to 7-0 to permit theantenna/controller pod 23 to be sutured to the patient's sternum,thereby ensuring that the antenna/controller pod 23 remains accessibleto the external antenna 14 and cannot migrate from a desiredimplantation site.

As shown in FIG. 101, the antenna/controller pod 23 encloses a printedcircuit board 76 that carries the antenna 83 and microcontrollercircuitry of the gastric band 21. The antenna 83 receives energy andcommands from the external control 10 (see FIG. 1), and supplies thosesignals to the microcontroller, which in turn powers the motor 66 of thedrive element 35. The circuitry of the antenna/controller pod 23 usesthe energy received from the incoming signal to power the circuit,interprets the commands received from the external control 10, andsupplies appropriate signals to the motor 66 of the drive element 35.The circuit also retrieves information regarding operation of the motor66 of the drive element 35 and relays that information to the externalcontrol 10 via the antenna 83. The circuit board preferably is coveredwith a water-resistant polymeric covering, e.g., Parylene, to permit usein the high (up to 100%) humidity environment encountered in the body.

The antenna/controller pod 23 includes a mechanical closure system thatis augmented by silicone glue so that the pod is fluid tight. Thissilicone glue also is used to protect soldered wires 79 from humidity.The antenna/controller pod 23 preferably is small, e.g., 16 mm×33 mm×4mm, to ensure compatibility with a standard 18 mm trocar and so as to becompatible with placement on the sternum. The antenna/controller pod 23preferably has a smooth, atraumatic shape to avoid tissue damage, hasgood mechanical strength to withstand handling with surgical graspersand to prevent mechanical deformation to the printed circuit board, andhas good electromagnetic permeability to allow efficient energytransmission through the antenna/controller pod 23. Theantenna/controller pod 23 preferably has a relatively thin planarconfiguration to avoid rotation of the antenna/controller pod 23 whenplaced under the skin, and may include holes that permit theantenna/controller pod 23 to be sutured in position.

With respect to FIG. 102, the antenna cable 24 is shown incross-section. The antenna cable 24 preferably is a coaxial shieldedcable encapsulated in a silicone tube 77 to provide biocompatibility.The tube 77 is selected to provide leak-proof encapsulation, withsufficient strength to permit the antenna cable 24 to be manipulatedwith atraumatic graspers. The braided shield 78 of the antenna cable 24prevents longitudinal deformation of the antenna cable 24, and surroundsfive helically wound insulated wires 79. Four of the wires 79 are usedto supply power to the micromotor of the drive element 35; the remainingwire and braided shield 78 are used to supply a signal from thereference position switch to the controller.

As discussed above with respect to FIG. 1, the gastric band 21 accordingto the present invention provides an integrated system for regulatingfood ingestion in the stomach of a patient, wherein variation of thediameter of the ring 22 may be adjusted without any invasive surgicalintervention. To accomplish this, the drive element 35 is linked to thesubcutaneous antenna/controller pod 23 to receive a radio frequencycontrol and power signal. In accordance with a preferred embodiment, themotor 66 of the drive element 35 has no internal energy supply, butrather is powered by the receiving circuit of the antenna 83 through arechargeable energy storage device, such as a capacitor. In particular,the receiving circuit converts radio frequency waves received from theexternal control 10 via the antenna into a motor control and powersignal. In accordance with an alternate embodiment, it is contemplatedthe drive element may be driven via an implantable rechargeable battery.

Power and Control Circuitry

Referring to FIG. 103, a preferred embodiment of the circuitry employedin the external control 10 and the gastric band 21 of the presentinvention is described, based on the principle of passive telemetry byFM-AM absorption modulation. The external control 10 is shown on theleft hand side of FIG. 18, and includes a microprocessor 80 coupled tothe control panel 12 and the display screen 13 (see FIG. 1). Theexternal control 10 produces a signal comprising one or more data bytesto be transmitted to the implantable antenna/controller pod 23 and thedrive element 35.

The external control 10 includes a modulator 81 for amplitude modulationof the RF wave from the RF generator 82, which signal is emitted by theexternal antenna 14. The emitted wave is received by the antenna 83 inthe antenna/controller pod 23, where the AM demodulator 84 extracts thedata bytes from the envelope of received RF signal. The data bytes thenare decoded and written into an EEPROM of the microcontroller 85. Aspecial code is used that allows easy decoding of the data by themicrocontroller 85, but also provides maximal security againstcommunication failure.

An external oscillator 86, which is a voltage controlled oscillator(VCO), provides a clock signal to the microcontroller 85. The externaloscillator 86 may consist of, for example, a relaxation oscillatorcomprising an external resistor-capacitor network connected to adischarging logic circuitry already implemented in the microcontrolleror a crystal oscillator comprising a resonant circuit with a crystal,capacitors and logic circuits. The former solution requires only twoadditional components, is suitable when the stability of the frequencyis not critical, and has low current consumption; the latter solutionprovides a more stable frequency, but requires a greater number ofadditional components and consumes more power. The external oscillator86 preferably comprises the external RC network, due to its simplicity.

The microcontroller 85 interprets the received instructions and producesan output that drives the motor 66 of the drive element 35. As discussedabove, the drive element 35 comprises a bi-directional stepper motor 66that drives the nut 60 through a series of reducing gears. Preferably,the two coils of the stepper motor 66 of the drive element 35 aredirectly connected to the microcontroller 85, which receives the workinginstructions from the demodulator 84, interprets them and provides thevoltage sequences to the motor coils. When the supply of voltage pulsesto the stepper motor 66 stops, the gears are designed to remainstationary, even if a reverse torque or force is applied to the nut 60by the tension element 32.

As also described above, use of a stepper motor 66 in drive element 35makes it is possible to obtain positional information on the nut 60 andthe tension element 32 without the use of sensors or encoders, becausethe displacement of the tension element 32 is proportional to the numberof pulses supplied to the stepper motor coils. Two signals are employedto ensure precise control, reference position signal S_(RP), generatedby the reference position switch of FIG. 13, and the drive elementsignal S_(A).

According to one preferred embodiment, signal S_(A) is the voltagesignal taken at one of the outputs of the microcontroller 85 that isconnected to the motor coils of the drive element 35. Alternatively,signal S_(A) could be derived from the current applied to a motor coilinstead of the voltage, or may be an induced voltage on a secondary coilwrapped around one of the motor coils of the drive element 35. In eithercase, signal S_(A) is a pulsating signal that contains information onthe number of steps turned by the rotor and further indicates whetherblockage of the mechanism has occurred. Specifically, if the rotor ofthe stepper motor fails to turn, the magnetic circuit is disturbed, andby induction, affects signal S_(A), e.g., by altering the shape of thesignal. This disturbance can be detected in the external control, asdescribed below.

Signals S_(A) and S_(RP) are converted into frequencies using theexternal oscillator 86, so that the voltage level of signal S_(A)applied to the external oscillator 86 causes the oscillator to vary itsfrequency F_(osc) proportionally to the signal S_(A). Thus, F_(osc)contains all the information of signal S_(A). When the crimped cap 45and the tension element 32 are in the reference position (that is, thering 22 is fully open), the reference position switch produces referenceposition signal S_(RP). Signal S_(RP) is used to induce a constant shiftof the frequency F_(osc), which shift is easily distinguishable from thevariations due to signal S_(A).

If the external oscillator 86 is a relaxation oscillator, as describedabove, signals S_(A) and S_(RP) modify the charging current of theexternal resistor capacitor network. In this case, the relaxationoscillator preferably comprises an external resistor-capacitor networkconnected to a transistor and a logic circuit implemented in themicrocontroller 85. With S_(A) and S_(RP), the goal is to modify thecharging current of the capacitor of the RC network to change thefrequency of the relaxation oscillator. If the charging current is low,the voltage of the capacitor increases slowly and when the threshold ofthe transistor is reached, the capacitor discharges through thetransistor. The frequency of the charging-discharging sequence dependson the charging current.

If the external oscillator 86 is a crystal oscillator, signals S_(A) andS_(RP) modify the capacitor of the resonant circuit. In this case, thecrystal oscillator circuit preferably comprises a crystal in parallelwith capacitors, so that the crystal and capacitors form a resonantcircuit which oscillates at a fixed frequency. This frequency can beadjusted by changing the capacitors. If one of these capacitors is aVaricap (a kind of diode), it is possible to vary its capacitance valueby modifying the reverse voltage applied on it, S_(A) and S_(RP) can beused to modify this voltage.

In either of the foregoing cases, signals S_(A) and S_(RP) are used tomodify at least one parameter of a resistor-capacitor (RC) networkassociated with the external oscillator 86 or at least one parameter ofa crystal oscillator comprising the external oscillator 86.

Referring still to FIG. 105, signals S_(A) and S_(RP), derived from thestepper motor or from the output of the microcontroller 85, may be useddirectly for frequency modulation b_(y) the external oscillator 86without any encoding or intervention by the microcontroller 85. By usingthe external oscillator 86 of the microcontroller 85 as part of the VCOfor the feedback signal, no additional components are required, andoperation of the microcontroller 85 is not adversely affected by thechanges in the oscillator frequency F_(osc). The oscillating signalF_(osc) drives the voltage driven switch 87 for absorption modulation,such that feedback transmission is performed with passive telemetry byFM-AM absorption modulation.

More specifically, signal F_(osc) drives the switch 87 such that duringthe ON state of the switch 87 there is an increase in energy absorptionby the RF-DC converter 88. Accordingly, therefore the absorption rate ismodulated at the frequency F_(osc) and thus the frequency of theamplitude modulation of the reflected wave detected by external control10 contains the information for signal S_(A). As discussed below, apickup 89 in the external control 10 separates the reflected wave whereit can be decoded by FM demodulation in the demodulator 90 to obtainsignal S_(A)′. This method therefore allows the transmission ofdifferent signals carried at different frequencies, and has theadvantage that the ON state of the switch 87 can be very short and theabsorption very strong without inducing an increase in averageconsumption. In this way, feedback transmission is less sensitive tovariation in the quality of coupling between the antennas 83 and 14.

In the external control 10, the feedback signal F_(osc) is detected bythe pickup 89 and fed to the FM demodulator 90, which produces a voltageoutput V_(OUT) that is proportional to F_(osc). V_(OUT) is fed to thefilter 91 and the level detector 92 to obtain the informationcorresponding to the drive element signal S_(A), which in turncorresponds to the pulses applied to the stepper motor coil. Themicroprocessor 80 counts these pulses to calculate the correspondingdisplacement of the tension element 32, which is proportional to thenumber of pulses.

Signal V_(OUT) also is passed through the analog-to-digital converter 93and the digital output is fed to the microprocessor 80, where signalprocessing is performed to detect perturbations of the shape of thefeedback signal that would indicate a blockage of the rotor of thestepper motor. The microprocessor 80 stops counting any detected motorpulses when it detects that the drive element is blocked, and outputs anindication of this status. The level detector 94 produces an output whenit detects that the demodulated signal V_(OUT) indicates the presence ofthe reference position signal S_(RP) due to activation of the referenceposition switch. This output induces a reset of the position of thetension element calculated by the microprocessor 80 in the externalcontrol. In this way, a small imprecision, e.g. an offset, can becorrected.

As described above, the external control 10 transmits both energy andcommands to the implantable controller circuitry in theantenna/controller pod 23. The external control 10 also receivesfeedback information from the implantable controller that can becorrelated to the position of the tension element 32 and the diameter ofthe ring 22. As will be apparent to one of skill in the art, theexternal control 10 and the implantable controller are configured in amaster-slave arrangement, in which the implantable controller iscompletely passive, awaiting both instructions and power from theexternal control 10.

Pressure Measuring

Measuring the applied pressure via the present ring 22 is very importantin ensuring that excessive pressure is not applied to the stomach. Assuch, the present invention incorporates the ability to measure theapplied pressure in a reliable, effective and convenient manner. Inaccordance with a first embodiment, and with reference to FIGS. 106 and107, the applied current for the motor 66 is measured and the measuredcurrent is utilized in determining the applied pressure and ultimatelyas a feedback system for measuring the functional state of the gastricband 21.

In accordance with this embodiment, the current is monitored via aclosed loop feedback system 1012 integrated into the operation of themechanical banding system 1 of the present invention. By incorporatingan electrical current measurement to measure electrical current beingdrawn by the motor 66 of the present banding system, the performance ofthe banding system may be evaluated for determination of, among otherfeatures, the applied pressure of the gastric band 21. The current drawnby the motor 66 is directly related to the force being applied by thebanding system. Any increase in the force applied by the gastric band 21is proportionally linked to an increase in current being drawn by themotor 66 of the gastric band 21. In practice, the current measured inaccordance with the application of the present invention is correlatedto the static force or pressure the ring 22 applies to the stomachtissue it encircles.

In addition to its use in measuring pressure, the monitoring of theapplied current may also be utilized in determining any loss ofperformance of the banding system due to component wear down, corrosion,etc.

Referring to FIG. 107, the closed loop feedback system 1012 includesleads 1016 accessing the current flowing from the power source 1018 tothe motor 66. The current is measured using a current sensing circuit1020 and the output current measurement 1022 is forward to themicrocontroller 85 of the present drive element 35 for action inaccordance with the goals of the present invention.

In accordance with an alternate embodiment, and with reference to FIG.108, measurements of the applied current are made using a Hall sensor1024 positioned about the wire 1026 supplying the motor 66 withelectrical power. When a Hall sensor 1024 is positioned above a currentcarrying wire 1026, it is capable of measuring current flow through thewire 1026 and ultimately the current being drawn for operation of themotor 66 as it constricts the ring 22 to apply pressure to the stomachwhich the ring 22 surrounds. In accordance with the embodiment disclosedherein, the measured current is derived from a voltage measurementacross a series of resistors 1028 in line with the power source 1018 forthe motor 66.

Regardless of the whether a hardwired circuit is employed or a Hallsensor is employed, the voltage is calculated by utilizing Ohms Law,that is, V=IR. Assuming a fixed resistance change in current, a currentis directly related to the voltage drop across the resistance of themotor 66. A typical sensing voltage might be between 50 mV and 200 mV.

In accordance with an alternate embodiment, and with reference to FIG.109, the tension applied by the gastric band 21, that is the appliedpressure of the gastric band 21, is monitored by a mechanical system1030. In particular, the tension applied to the flexible tension element32 is monitored utilizing a strain gauge 1032 acted on by the threading1034 of the tension element 32. By monitoring the force applied to thestrain gauge 1032, the operator is provided with an indication whenfail-safe action is necessary.

The strain gage 1032 is preferably coupled to the nut 600 on the driveelement housing 53, for example, by means of a cantilevered beam 1036.The interaction of the nut 600 with the threading 1034 of the tensionelement 32 provides highly accurate force measurements concerning therelationship between the nut 600 and the threading 1034 of the tensionelement 32. By monitoring the force measurements, the pressure appliedby the gastric band 21 is determined and operators of the gastric band21 are readily able to determine when fail-safe action is necessarybased upon a detection of excess tension in the gastric band 21.

In accordance with a variation of the use of a strain gauge, the straingauge 1032 may straddle threading on the tension element 32 so as toidentify the applied force. See FIG. 110. To identify the applied forcethe strain gauge output would be connected to a circuit, such as ananalog to digital converter (A/D) or microcontroller 1060, that convertsthe strain into an applied force. The A/D or microcontroller 1060 wouldprovide force data to a telemetry circuit 1062 which in turn would sendthe data to the external reading device 1064. The applied force could becompared to a force threshold (either dynamic or static) either by theinternal circuitry 1060 or by the external reading device 1064 which inturn would provide and indication to the state of the drive mechanism. Ahigher force/tension in either movement direction may indicate amechanical failure in the drive mechanism.

As with the prior embodiment, and in addition to its use in measuringtension along the gastric band 21, the monitoring of the forceencountered by the strain gauge 1032 may also be utilized in determiningany loss of performance of the banding system due to component weardown, corrosion, etc. As such, the strain gauge is preferably linked toa feedback system controlling operation of the drive element 35. It isalso contemplated that in addition to a strain gage, position/proximitysensors may be employed, Hall effect sensors may be employed, contactsensors may be employed or a microswitch may be employed.

In accordance with yet a further embodiment as shown with reference toFIG. 111, and where a fluid filled bladder 1038 is incorporated alongthe internal surface 1040 of the ring 22, the pressure of the fluidwithin the bladder 1038 is measured to provide an indication as to thepressure being applied to the stomach via the present banding system 1.

In accordance with this embodiment, a fluid bladder 1038 is formed alongthe internal surface 1040 of the mechanical gastric band 21. The fluidbladder 1038 is formed and positioned such that it directly interfaceswith tissue. In accordance with a preferred embodiment, the fluidbladder 1038 may be integrally formed with the gastric band or it may beselectively secured thereto for use in accordance with the presentinvention. As such, and where the fluid bladder 1038 is selectivelysecured to the gastric band 21, it may be secured to the gastric band 21prior to or during installation (implantation). A pressure sensor 1042is linked to the fluid bladder 1038 allowing for remote monitor of thefluid pressure within the bladder 1038.

By constructing the ring 22 in such a manner, not only is a softertissue interface provided by the fluid bladder 1038, but the inclusionof the fluid bladder 1038 allows for the ability to add a pressuresensor 1042 in the fluid path to measure the fluid pressure in thebladder 1038. When the gastric band 21 is wrapped around the stomachtissue, the monitored pressure within the bladder 1038 relates to thepressure exerted on the tissue. This pressure reading is then used as aprimary or secondary feedback to control the applied restrictionemployed in accordance with the gastric band 21 of the presentinvention.

In practice, and in accordance with a preferred embodiment as disclosedherein, the bladder 1038 is pre-filled with fluid and calibrated priorto implantation. While pre-implantation calibration is contemplated, itis conceived that calibration may be performed after implantation inaccordance with the present invention. As such, the fluid bladder may beadjusted to ensure proper calibration. Such adjustments are achieved byconnection of the fluid bladder to a filling tube via a port formed inthe fluid bladder. The bladder 1038 is preferably made of silicone oranother biocompatible material and is preferably filled with anon-aqueous fluid or gel, for example, silicone or fluoro-silicone oil.The pressure 1042 is preferably a piezoresistive or capacitive sensordesigned for implantation in a hermetic package. The pressure 1042 isconnected to a telemetry circuit 1044 allowing pressure to be readoutside the body using an external reading device 1046.

As with the previously discussed embodiments for measuring the appliedpressure of the gastric band 21, the pressure bladder 1038 may alsoserve as an indicator to the functional state of the mechanical gastricband 21. Pressure should increase when the gastric band 21 is tightenedand decrease when the gastric band 21 is loosened. If the mechanicalsystem is not functioning correctly, there will be no change inpressure.

In addition to providing a fail-safe mechanism for operation of thepresent ring 22, loading information garnered in the manner discussedabove, may also be used to aid the surgeon in correctly setting theband's initial degree of restriction during band implantation. That is,the loading information could also be used to help ensure that the bandis initially implanted with the correct degree of restrictiveadjustment. In this case an indication of tension element loading wouldprovide surgeons (especially novice ones) with an indication of whetherthey've sufficiently tightened the band onto the tissue to achieve thedesired constriction while also making sure that they haven'texcessively tightened the band onto the tissue and/or undesirablyapproached the tension element's yield point.

The load measurements may also be used to prevent over-tightening theband during extended use. In particular, the loading information couldalso be used in an alternative manner if the band has auto-tightnessadjustment capability. In this case the surgeon may or may not bepresent at the time the tension of the tension element is beingadjusted. In this scenario, the load and/or strain measurements could beused to signal the control unit of the motor to either stop tighteningthe band if a pre-set load threshold is reached or actually reverse thedirection of the motor to decrease tension element loading if thethreshold has already been exceeded. One way to ensure that the loadingthreshold is never exceeded is to control the flow of current to themotor using commonly known techniques, such as current clipping, toensure that the motor is never able to build up enough torque toover-tighten the tension element. Alternatively, an electrical fuseelement could be used in conjunction with the current supplied to themotor such that the fuse would trip and either limit or release loads onthe tension element if the current supplied to the motor ever exceeds anallowable threshold.

In addition to the measuring techniques discussed above, these benefitscould be embodied by use of any of the load measuring techniques, suchas, measuring the motor torque. In particular, the tension on thetension element may be derived from motor torque. The algorithm used inthis method is explained representatively at:http://www.dynetic.com/faq.htm., which states, “The torque requirementfor an application can be calculated, measured directly using a torquemeasuring deice (torque watch), or measured indirectly using a DC motor.When using a motor, measure the current drawn of the motor under load,and calculate the torque using the equation below:

T=(I−I _(NL))×(K _(T) ×N×h)

Where,

-   -   I=Current    -   T=Torque    -   K_(T)=Torque Constant    -   N=Gear Ratio (Equals 1 if there is no gearbox)    -   h=Gearbox Efficiency (Equals 1 if there is no gearbox)    -   I_(nL)=No-Load Current

Please be aware this equation approximates the true load torque and doesnot take thermal conditions into consideration. The results arereasonably close and suitable for most purposes.”

The current may be determined by measuring the current across a shuntresistor in series with the motor at the power source. Themicrocontroller will measure the voltage across the resistor and convertthe value to current using Ohm's Law (I=V/R where I=current, V=voltageand R=Resistance across the shunt resistor) in order to determinetorque.

This value may be converted to tension since the tension element is ascrew thread or cable.

In general, a representative conversion equation for torque to axialload (cable tension) is:

T=DF

Where,

-   -   T=Torque required    -   F=Desired cable tension    -   D=cable thread nominal diameter (major dia)

Since it is not generally recommended that induced stress exceed a safefraction of the yield strength of the tension element, it may bedesirable to introduce a fractional coefficient c (less than or equalto 1) in the equation:

T=cDF

Expressed in terms of cable tension:

F=T/cD

Since this relationship is linear, however, any correlations such asthose discussed below to band adjustments may be made using torque ortension. Thus, current, torque or cable tension may all be used as anadjustment parameter, much the same as the pressure measurements asdescribed in U.S. Patent Application Publication No. 2006/0211913,entitled “NON-INVASIVE PRESSURE MEASUREMENT IN A FLUID ADJUSTABLERESTRICTIVE DEVICE”, which is incorporated herein by reference.

As discussed above, the tension upon the tension element may be measuredby monitoring component strain. The tension may be measured directly viaa strain gauge. The strain gauge may be positioned in a number oflocations such that the tension would cause a strain, i.e.,

-   -   on the tension element 32 itself, measuring stretch of the        tension element 32 (See FIG. 110)    -   between the rear hub and the nut 60 (see FIG. 109);    -   between the tension element 32 and an axially grounded portion        of the hub.

The strain read by the strain gauge may be translated to tension element32 tension by

the association:

σ=E ε

Where,

-   -   σ=the cable stress=F_(t)/A    -   F_(t)=the cable tension    -   A=the cross sectional area of the cable    -   E=the elastic modulus of the material    -   ε=the strain in the cable

So,

F_(t)=E ε A

In accordance with yet another embodiment, the strain gauge locationcould be used as a compressive force gage if the nut is free totranslate slightly with the thread. The gauge would be positioned underthe nut on the side opposite the direction of translation of thethreaded shaft and the nut would impose a compressive force on to thegauge when the band is adjusted. In a manner similar to the tensionmeasured above the force could also be measured with compression aswell. Thin film load cells are commercially available and can be foundin U.S. Pat. No. 6,272,936. This circuit can be made to fit a very tinyspace in-between the nut 60 and the hosing plate.

In accordance with yet another embodiment as shown with reference toFIG. 112, the axial loads on the tension element 32 may be measured. Inaccordance with such and embodiment, the tension force between the endof the spring element (that is the tension member 32), and the threadedshaft at the free end 34 of the tension element 32 is measured. A smalltransducer 1032 is attached that measures the axial load seen by thethreaded shaft as the gastric band 21 is adjusted. This could also beemployed at various locations along the tension element 32, such asthose indicated by the red circles.

Operational Modes

Referring to FIG. 103, some of the safety features of the banding systemof the present invention are described. As discussed above with respectto FIG. 105, both power and control signals are provided to theimplantable controller from the external control 10. Because power isdelivered to the implantable controller via magnetic induction, theamount of energy delivered to the controller depends on the quality ofthe coupling between the external antenna 14 and the antenna circuitrycontained within the antenna/controller pod 23.

The quality of the coupling may be evaluated by analyzing the level ofthe feedback signal received by the external control 10, and a metriccorresponding to this parameter may be displayed on the signal strengthindicator 17, which includes 6 LEDs (corresponding to six levels ofcoupling). If the coupling between the antennas 14, 83 is insufficient,the motor 66 of the drive element 35 may not work properly, resulting inan inaccurate adjustment of the gastric band 21.

Accordingly, in a standard mode of operation, adjustment may be madeonly if the coupling quality is strong enough, as indicated by having atleast LED 5 or LED 6 in FIG. 103 illuminated. If, on the other hand,poor coupling exists (e.g., one of the first four LEDs are illuminated)it is still possible to perform some adjustment of the gastric band 21,although the adjustment may be inaccurate.

The design of the external control 10, in combination with the patientmicrochip card 16 (see FIG. 1), also ensures a high degree of efficacyand safety. First, as contemplated for use with the gastric band 21 ofthe present invention, the external control 10 is intended primarily foruse by a physician in an office or hospital setting, and not by thepatient alone. Of course, in alternative embodiments, such as to treaturinary or fecal incontinence, it would be essential to provide anexternal control 10 for use by the patient. The simplicity of the designof the external control 10 and ease of use would provide no impedimentto use by the patient for such embodiments.

As discussed with respect to FIG. 1, patient microchip card 16 stores,among other data, a serial number identifying a corresponding gastricband 21 and the diameter of the ring 22 upon completion of the previousadjustment. When the external control 10 first transmits energy to theimplantable controller of the gastric band 21, the gastric band 21identifies itself to the external control 10. In the standard mode ofoperation, the serial number stored on the patient microchip card 16must match that received from the gastric band 21, otherwise noadjustment is permitted.

As a fail-safe, however, the physician still may adjust the gastric band21 even if the patient has lost or misplaced his microchip card 16. Inthis case, the external control 10 may be set in a “no card mode”. Inthis mode, the information displayed on the display screen 13 of theexternal control 10 corresponds only to the relative variation of thegastric band 21 during that adjustment session, and is no longerindicative of absolute diameter. When the physician activates this mode,an emergency bit is set in the memory of the implantable controller toindicate the “no card mode”. In subsequent adjustment sessions, theimplantable controller will signal that the gastric band 21 was adjustedin the “no card mode” and all further adjustments will be reported on arelative basis. If the patient again locates the microchip card 16, theemergency bit may be cleared by fully opening the gastric band 21 andthus reaching the reference contact, which re-initializes the position.Subsequent adjustments will again be managed in the standard mode ofoperation.

During adjustment of the ring 22, a physician places the externalantenna 14 in a face-to-face position on the skin of the patientrelative to the antenna/controller pod 23 of the ring 22, and to receivefeedback information from which the constricted diameter of the ring 22may be computed. In accordance with the principles of the presentinvention, it is possible to vary the diameter of the ring 22 withouthaving to undertake invasive surgical intervention, and this variationmay be carried out at will, because multiple control cycles may becarried out at regular or irregular intervals, solely under the controlof the treating physician.

The banding system of the present invention is expected to beparticularly reliable, relative to previously-known hydraulic bands thatcan be adjusted by the patient, because only the physician typicallywill have access to the external control box needed to adjust the ring.For a ring embodiment intended for treatment of morbid obesity, thepatient therefore does not have free access to any means to adjust thediameter of the ring.

Moreover, because the gastric band of the present invention provides aprecise readout of the current diameter of the ring in the standard modeof operation, it may not be necessary for the patient to ingest aradiographic material (e.g., barium dye) to permit radiographicvisualization of the ring to confirm the adjusted size. The process ofadjusting the band accordingly may be carried out in a doctor's office,without the expense associated with radiographic confirmation of suchadjustments. In addition, the self-blocking configuration of the tensionelement and nut, in combination with the mechanical nature of thegastric band, overcome problems associated with previously-knownhydraulically actuated gastric band systems.

Methods of Implantation and Removal

Referring now to FIG. 104, the gastric band 21 of the present inventionis shown implanted in a patient. The ring 22 is disposed encircling theupper portion of the patient's stomach S while the antenna/controllerpod 23 is disposed adjacent to the patients sternum ST. Theantenna/controller pod 23 is located in this position beneath thepatients skin SK so that it is easily accessible in the patients chestarea to facilitate coupling of the antenna/controller pod 23 to theexternal antenna 14 of the external control 10 (see FIG. 1).

Other Features

In addition to the features discussed above, the present inventionprovides a mechanism for protecting the implanted electronics fromelectromagnetic interference (for example, from MRI). In particular, theelectronics of the device are encased in a titanium case 1202 (see FIG.72) and the antenna 1283 is moved external to the titanium case 1202. Inthis way, the electronics may be implanted deeper into the body cavity,leaving only a thin antenna near the surface of the skin.

In addition, time limit warning on the packaging of the device may beavoided

-   -   where the gastric band is prefilled with fluid or gel, air would        not permeate the silicone. The fluid could be incorporated        during manufacturing or injected once the device is opened in        the operating room. This would also improve the tissue interface        of the gastric band by making it softer.    -   if the gastric band were shipped in fluid or instructed to place        the device in a saline bath when opened, it could stay in place        indefinitely.    -   If the silicone is coated with parylene, titanium or similar        compositions to reduce permeation rates thereby increasing the        open air time.    -   If the balloon is left unsealed. Since the band is mechanical        and not hydraulic, the balloon has no functional need to be        sealed.

As stated in the System Overview portion of the present application, thetelemetrically-powered and controlled ring system of the presentinvention has numerous applications apart from gastric banding for thetreatment of morbid obesity. For example, the ring system of the presentinvention may advantageously be used for the treatment of fecalincontinence, ileostomy, coleostomy, gastro-esophageal reflux disease,urinary incontinence and isolated-organ perfusion.

For treatment of fecal incontinence, the ring may be used with little orno modifications. In addition, because the ring adjustment procedurewill be performed by the patient on at least a daily basis, a portableuser-friendly external control may be used. In addition, because thering will regularly be transitioned between the closed and fully openedposition, the patient microchip card is unneeded. Instead, the fullyclosed position may be stored in the memory of the implantablecontroller, and read by the external remote at each use (subject toperiodic change by the physician).

A similarly modified device could be used by patients who have undergoneileostomy or coleostomy, or disposed surrounding the esophagealjunction, to treat gastro-esophageal reflux disease.

For treatment of urinary incontinence, the ring may be further modifiedto minimize the volume of the ring surrounding the urethra by moving thedrive element motor to a location elsewhere in the lower abdomen orpelvis, and coupling the drive element to the motor via a transmissioncable.

The present invention also may be beneficially employed to performisolated-organ perfusion. The treatment of certain cancers requiresexposure to levels of chemotherapy agents that are too high for systemiccirculation. It has been suggested that one solution to this problem isperform an open surgery procedure in which blood flow to the cancerousorgan is stopped and quiescent blood replaced by circulation from anexternal source containing a desired dose of drug. Individual ormultiple rings of the present invention may be used as valves to isolatethe cancerous organ and permit perfusion of the organ with high doses ofdrugs. Such procedures could thus be performed on a repetitive basiswithout surgery, thereby reducing the trauma and the risk to the patientwhile improving patient outcomes.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration. Further variations will beapparent to one skilled in the art in light of this disclosure and areintended to fall within the scope of the appended claims.

As discussed above, it is possible to make highly accurate loadmeasurements regarding the load applied by the ring in accordance withthe present invention. This information may be used to dynamicallyadjust the band's degree of restriction to optimize weight loss. Thismay prove helpful to surgeons in making a correlation between tension onthe tension element and how tightly the band is tightened on tissue.Much the same as the pressure measurements as described in U.S. PatentApplication Publication No. 2006/0211913, entitled “NON-INVASIVEPRESSURE MEASUREMENT IN A FLUID ADJUSTABLE RESTRICTIVE DEVICE”, which isincorporated herein by reference; that is, the manner in which pressuremagnitude and pulse counting of peristaltic waves is used as a targetagainst which to adjust, the load or strain measurements may be used ina similar fashion as a measure of peristaltic pressure. Such systems aredisclosed in U.S. Patent Application Publication No. 2006/01898888,entitled “DEVICE FOR NON-INVASIVE MEASUREMENT OF FLUID PRESSURE IN ANADJUSTABLE RESTRICTION DEVICE”, and U.S. Patent Application PublicationNo. 2009/0187202, entitled “OPTIMIZING THE OPERATION OF A RESTRICTIONSYSTEM”, which are also incorporated by reference. Pressure waves fromesophageal peristalsis will cause tension changes in the cable which maybe read and correlated to proper or improper adjustment. Pulses may becounted from this same means, along with pulse width, duration, etc.Much of the information that can be gained will be able to be derivedform the present mechanism.

Multiple methods of storing the measured loads on the band arediscloses, which include but are not limited to:

-   -   Storing motor torque;    -   Storing mechanical strain;    -   Storing compressive and axial loads.

With regard to storing motor torque, the component torque, as describedabove, may also be stored for later analysis by a torque measuringdevice (torque watch). Simpler models would just record and store peakvalues, which may be sufficient for this application. Alternatively, amore complex model would allow for storage of continuously obtainedtorque information. Due to storage capacity, it is likely that the datawould need to be recorded in set increments and be downloadedperiodically. Alternately, if the torque was measured indirectly using aDC motor as described above, a multimeter may be used to record andstore peak values and/or continuously obtain information which couldthen be converted to torque via the above equations.

As to storing mechanical strain, the component strain, as describedabove, may also be stored for later analysis by a strain gauge. Simplermodels would just record and store peak values, which may be sufficientfor this application. Alternatively, a more complex model would allowfor storage of continuously obtained strain information. Due to storagecapacity, it is likely that the data would need to be recorded in setincrements and be downloaded periodically.

Compressive and axial loads may also be stored, as described above. Thisinformation is stored for later analysis by a strain gauge. A basicforce gauge may be used to store compressive and axial loads. Simplermodels would just record and store peak values, which may be sufficientfor this application. Alternatively, a more complex model would allowfor storage of continuously obtained torque information.

Stored information to interested parties (i.e., Surgeon, Primary CarePhysician (PCP), Patient, etc.) may be relayed to other parties for useat remote locations. With regard to the relay of information to thesurgeon/PCP, a surgeon or primary care physician may be interested inobtaining and using the information gathered to make determinationsabout the restriction provided by the band and/or complications arisingfrom the tightness of the band. As a result, it is desirable that theinformation measured and stored as described above is also accessible bythe surgeon or PCP. One mechanism for achieving this would be to use anexternal data logger which would be worn by the patient. Informationstored in this device could be downloaded by the surgeon or PCP by meansof a USB port. For example, see U.S. Patent Application Publication No.2006/0199997, entitled “MONITORING OF A FOOD INTAKE RESTRICTION DEVICE”and U.S. Patent Application Publication No. 2008/0249806, entitled “DATAANALYSIS FOR AN IMPLANTABLE RESTRICTION DEVICE AND A DATA LOGGER”, whichare hereby incorporated by reference.

As to the relay of information to the patient, patients would beinterested in obtaining some information about the status of therestriction in their band for various reasons. For example, one reasonwould be to indicate that there may be a problem with their implant anddirect them to visit their surgeon. Since it would probably not benecessary or useful for them to receive numerical information about thetorque, strain or load present in their band, a different type ofrelaying method would be important. One option would be an audible noise(i.e., alarm) which would indicate to them if there was a potentialissue with their implant. Alternatively, if they were wearing anexternal data logger as described above, a visual light (i.e., flashingred or green) could indicate the status of their implant.

While the preferred embodiments have been shown and described, it willbe understood that there is no intent to limit the invention by suchdisclosure, but rather, is intended to cover all modifications andalternate constructions falling within the spirit and scope of theinvention.

1. Apparatus for regulating the functioning of a patient's organ orduct, comprising: an elongated member having a first end and a secondend; a fastener disposed on the first end of the elongated member, thefastener configured to engage the second end of the elongated member sothat the elongated member forms a loop around the organ or duct; atension element disposed for movement within the elongated member; adrive element associated with and engaging the tension element forcausing the tension element to control the tension applied by theelongated member against a patient's body organ or duct; and a loadmonitor ensuring that excessive pressure is not applied to a patient'sbody organ or duct.
 2. The apparatus according to claim 1, wherein theload monitor includes a monitoring circuit monitoring current drawn bythe drive element.
 3. The apparatus according to claim 2, wherein driveelement is motor.
 4. The apparatus according to claim 2, wherein themonitoring circuit is a closed loop feedback circuit.
 5. The apparatusaccording to claim 4, wherein the monitoring circuit includes leadsaccessing current flowing from a power source to a motor of the driveelement.
 6. The apparatus according to claim 5, wherein the current ismeasured using a current sensing circuit and output current measurementis forward to a microcontroller for control of the drive element.
 7. Theapparatus according to claim 2, wherein the monitoring circuit includesa Hall sensor positioned about a wire supplying a motor of the driveelement with electrical power.
 8. The apparatus according to claim 1,wherein load monitor is a strain gage.
 9. The apparatus according toclaim 8, wherein the drive element includes a motor acting uponthreading of the tension element and the strain gage measures tensionapplied to the threading of the tension element.
 10. The apparatusaccording to claim 1, wherein the load monitor includes a pressuremonitor associated with a fluid filled bladder forming part of theelongated member.
 11. The apparatus according to claim 10, wherein thefluid filled bladder is formed along the interior surface of theelongated member.
 12. The apparatus according to claim 10, wherein thefluid bladder is a separate component and may be added or fixedlyattached to the elongated member prior to or during installation. 13.The apparatus according to claim 10, wherein the fluid filled bladder ispre-filled with fluid and calibrated prior to implantation.
 14. Theapparatus according to claim 10, wherein the fluid filled bladder may befluid calibrated post implantation.
 15. The apparatus according to claim10, wherein the fluid filled bladder is adjustable.
 16. The apparatusaccording to claim 10, wherein the fluid filled bladder is provided witha port in fluid communication with a filling tube that extends from thefluid bladder.
 17. The apparatus according to claim 10, wherein fluidwithin the fluid bladder is a non-aqueous fluid or gel.
 18. Theapparatus according to claim 1, wherein load monitor includes a torquesensor measuring the motor torque.